Some are irritating, but there is only one that seriously annoys me: 'This is the exception that proves the rule.'
In science and logic, the exception disproves the rule. I wonder if the phrase originated in some grammatical context, perhaps in some notion that every grammatical rule must have one or more exceptions. But that's wrong, too.
Just because 'the exception that proves the rule' is a paradox, it doesn't mean its grammatically incorrect. Something like 'the exception is proves the rule' would be so, but 'exception that prove the rule' doesn't. Also, I think that the rules of grammar are not as a cast in stone as you make out, any more the rules of spelling-they keep changing.
A set of cliches that do bug me is the American 'business-speak' ones about "Running it up the flag pole ...." "Putting it in a bowl and see what the cat licks up....." and the ultimate - "Thinking outside the box ...." who conceives this nonsense? Can someone tell them it has the opposite of the desired effect - they don't sound erudite and smart, they sound facile and ...er...cliched!
"The exception which proves the rule" was used in the old-fashioned meaning of the word "prove" i.e to test; to verify the boundaries of; not in the modern legal/logical sense.
Well done bernardo! As the old saying goes, 'Not many people know that'. In fact, I couldn't have put it better myself. Except perhaps, somewhat pedantically (grammar-wise), to say "the exception that proves the rule"