Not about writer's block

I know I said I was going to write about writer's block - but that would be soooo boring if I did it day after day!

So instead I'm going to ponder.

Do people send you books? People send me books, from time to time, and I'm always very grateful. If they are books for review, then I review them (obviously, you might think, but you'd be amazed how many supposed reviewers never actually write the review they promised the author/editor) but what - I wonder - do people expect when they just send me a book?

I write back and say thank you, of course. But are they expecting me to comment on the book, or laud it to my friends, or what? I always feel a little gauche and unsure how to respond.

I have a rule about unpublished fiction, which is if people I know send it to me, I critique it and send it back (only once for free, mind you, after that they can pay my going rate). If strangers send it to me I offer them a quotation for editing and critiquing. I suspect this has cost me acquaintences over the years, but I'm not in the business of boosting people's egos - I'm in the business of improving prose (mine and others) and I'm simply not interested in making nice about writing. Making nice isn't enough - making better is.

Do other writers get sent books that they haven't solicited? If so, what do you do about them?