A little while ago, a survey was held among alumni of the English department of the University of Leiden to find out about their attitudes to particular usage problems.
The items surveyed can be found in David Crystal’s Encyclopedia of the English Language, under Grammatical Top Ten (1995:194):
- between you and I
- split infinitives (to definitely ask)
- placement of only (I only saw Jane or I saw only Jane)
- none with plural verb (none were left on the table)
- different from rather than to or than
- sentences ending with a preposition (that was the clerk I gave the money to)
- I shall, not I will
- hopefully at the beginning of a sentence
- whom for who (the man whom I saw)
- double negatives.