Dear Plinky, today you asked what my pet peeve is. It would have to be authors who insist on ending their letters with “please do not hesitate to contact me”. I shudder every time I see it.
All the advice I’ve read online is that it’s okay to use a double negative in collequial or informal settings, however they should be avoided in formal situations. One writing expert even went so far as to say “using double negatives is even more corrosive than single negatives”.
So why do people continue to use such an antiquated phrase? It’s almost as bad as inserting a comma after the salutation and/or complimentary close. Now every time I see a ‘please do not hesitate’, I hit the delete key as fast as I can and replace it with “if you have any queries, please contact me”.