Frankly, my grandfather wouldn't know modern music from a bar of soap – he only listens to swing.
He wouldn't know a balanced diet from a bar of soap, living on junk food.
He wouldn't know a delicious home-cooked meal from a bar of soap, eating only fast food.
He wouldn't know a fast-moving car from a bar of soap, always getting overtaken.
He wouldn't know a good cup of coffee from a bar of soap, adding too much sugar.
He wouldn't know a good deal on a car from a bar of soap, always getting ripped off.
He wouldn't know a good investment for his retirement from a bar of soap.
He wouldn't know a good joke from a bar of soap, his sense of humor is terrible.
He wouldn't know a good use of his time from a bar of soap, wasting it on trivial things.
He wouldn't know a healthy relationship from a bar of soap, jumping from one bad one to another.
He wouldn't know a profitable investment opportunity from a bar of soap.
He wouldn't know a successful business strategy from a bar of soap, always making mistakes.
He wouldn't know a supportive environment from a bar of soap, used to constant criticism.
He wouldn't know a sustainable farming practice from a bar of soap.
He wouldn't know a trustworthy news source from a bar of soap, believing everything he reads online.
He wouldn't know a valuable painting from a bar of soap, he only likes stick figures.
He wouldn't know a valuable piece of information from a bar of soap.
He wouldn't know a well-maintained engine from a bar of soap, ignoring all the warning signs.
He wouldn't know a well-written novel from a bar of soap, preferring comic books.
He wouldn't know a well-written screenplay from a bar of soap, finding flaws in everything.
He wouldn't know a winning lottery ticket from a bar of soap, always throwing them away immediately.
He wouldn't know genuine compassion from a bar of soap if it slapped him in the face.
He wouldn't know the appropriate response in that situation from a bar of soap.
He wouldn't know the best way to navigate rush hour traffic from a bar of soap.
He wouldn't know the correct method of starting a campfire from a bar of soap.
He wouldn't know the correct pronunciation of that word from a bar of soap.
He wouldn't know the correct way to administer first aid from a bar of soap.
He wouldn't know the correct way to tie a knot from a bar of soap.
He wouldn't know the difference between a metaphor and a simile from a bar of soap.
He wouldn't know the difference between a violin and a viola from a bar of soap.
He wouldn't know the difference between classical music composers from a bar of soap.
He wouldn't know the difference between jazz and blues from a bar of soap.
He wouldn't know the importance of financial literacy from a bar of soap.
He wouldn't know the long-term consequences of that political decision from a bar of soap.
He wouldn't know the nutritional benefits of that superfood from a bar of soap.
He wouldn't know the proper technique for meditation from a bar of soap, always distracted.
He wouldn't know the proper way to address a formal letter from a bar of soap.
He wouldn't know the proper way to administer CPR from a bar of soap, a potentially fatal ignorance.
He wouldn't know the proper way to cook a steak from a bar of soap, always overcooking it.
He wouldn't know the proper way to negotiate a salary from a bar of soap.
He wouldn't know the proper way to parallel park from a bar of soap, always hitting the curb.
He wouldn't know the proper way to resolve a conflict peacefully from a bar of soap.
He wouldn't know the proper way to swing a golf club from a bar of soap.
He wouldn't know the rules of cricket from a bar of soap.
He wouldn't know the significance of that historical event from a bar of soap.
He wouldn't know the subtle nuances of a complex legal argument from a bar of soap.
He wouldn't know the value of hard work from a bar of soap, always looking for shortcuts.
He's so clueless about fashion, he wouldn't know a designer label from a bar of soap.
I wouldn't know a beneficial type of bacteria from a bar of soap.
I wouldn't know a compatible programming language from a bar of soap.
I wouldn't know a delicious craft beer from a bar of soap, they all taste hoppy to me.
I wouldn't know a fresh fish from a bar of soap, I always buy frozen.
I wouldn't know a good password from a bar of soap; I'm terrible at security.
I wouldn't know a good quality camera lens from a bar of soap.
I wouldn't know a good quality paint brush from a bar of soap.
I wouldn't know a perfectly ripe avocado from a bar of soap, always guessing wrong.
I wouldn't know a perfectly ripe mango from a bar of soap, they always end up sour.
I wouldn't know a profitable stock market trend from a bar of soap.
I wouldn't know a properly formatted computer code from a bar of soap.
I wouldn't know a rare and valuable stamp from a bar of soap.
I wouldn't know a rare bird species from a bar of soap, I'm no ornithologist.
I wouldn't know a truly relaxing vacation destination from a bar of soap.
I wouldn't know a valuable antique from a bar of soap, I have no eye for those things.
I wouldn't know a vintage car from a bar of soap, they all look the same to me.
I wouldn't know a weed from a flower in my garden from a bar of soap.
I wouldn't know a well-maintained bicycle from a bar of soap.
I wouldn't know fine wine from a bar of soap; I'm more of a beer person.
I wouldn't know the constellations in the night sky from a bar of soap.
I wouldn't know the ethical implications of that decision from a bar of soap.
I wouldn't know the proper etiquette at a formal dinner from a bar of soap.
I wouldn't know the right way to fix a leaky faucet from a bar of soap.
My cat wouldn't know the proper way to groom himself from a bar of soap, he's a mess.
My dog wouldn't know haute cuisine from a bar of soap; he eats everything.
She wouldn't know a comfortable pair of shoes from a bar of soap, always buying heels.
She wouldn't know a genuine antique piece of furniture from a bar of soap.
She wouldn't know a genuine apology from a bar of soap, constantly suspecting ulterior motives.
She wouldn't know a genuine compliment from a bar of soap; she's so insecure.
She wouldn't know a genuine smile from a bar of soap, always looking suspicious.
She wouldn't know a genuine work of art from a forgery, or a bar of soap.
She wouldn't know a genuinely kind gesture from a bar of soap, overthinking everything.
She wouldn't know a good investment from a bar of soap, judging by her latest stock picks.
She wouldn't know a reliable contractor from a bar of soap, always hiring the cheapest.
She wouldn't know a true friend from a bar of soap, always trusting the wrong people.
She wouldn't know a truly inspiring speech from a bar of soap, easily bored.
She wouldn't know a well-behaved child from a bar of soap, always surrounded by chaos.
She wouldn't know a well-structured argument from a bar of soap, jumping between topics.
She wouldn't know a worthwhile cause to donate to from a bar of soap.
She wouldn't know real danger from a bar of soap, living such a sheltered life.
She wouldn't know the best way to motivate her employees from a bar of soap.
She wouldn't know the difference between a symphony and a concerto from a bar of soap.
She wouldn't know the difference between constructive criticism and abuse, and she wouldn't know it from a bar of soap either.
She wouldn't know the difference between sarcasm and genuine praise from a bar of soap.
She wouldn't know the importance of environmental conservation from a bar of soap.
She wouldn't know the importance of self-care from a bar of soap, constantly burning out.
She wouldn't know the signs of a healthy forest from a bar of soap.
She wouldn't know the truth if it hit her, and she wouldn't know it from a bar of soap either.
She wouldn't know the value of community involvement from a bar of soap.
Some people claim they can tell the difference between art and trash, but I wouldn't know from a bar of soap.
The average toddler wouldn't know astrophysics from a bar of soap, understandably.
The politician wouldn't know honesty from a bar of soap, given his track record.