On here there seems to be a very polarised view.
Can't buy:
Chocolates (too generic)
Anything practical (like the aforementioned hoover)
Anything that might be used by others in the family
Jewellery (unless you know exactly what they want)
Clothes (unless the above and you get the size right)
Books (they might have got it)
Anything cheap (even if it's something they like)
Anything expensive (because they'd have rather something else for that amount of money)
Anything from MIL (bound to be wrong)
etc.
I have to be honest and think that it's not actually the present that's the issue. When people are not in the best place with a relationship it's very easy to read into anything malice aforethought.
Some people are great at buying presents. Some people are terrible.
Some of the latter put great effort in, and still get it wrong. Some people don't bother putting any effort in at all.
I think the majority of times when the present ends up on here, it was probably bought either in innocence or in genuine thought that it was a good idea.
There was the year df told dm that he'd got her an amazing present and he couldn't wait for her to have it. He meant it. She nearly crowned him with it.
It was a book entitled something along the lines of "How to be a housework goddess and have time to do other things too."
He'd thought it was perfect. She did not. 
There was no nastiness involved. It was a pity that he'd mentioned so often that he'd got a fantastic present. But then df's idea of a perfect present would be a box of wall plugs or a can of varnish.
There was a poem I learnt at junior school:
When Bill gives me a book, I know
It's just the book he wanted, so
When I give him a ping-pong set
He's sure it was what I hoped to get
So after Christmas we arrange
A little Christmas gift exchange
I give the book to Bill, and he
Gives back the ping-pong set to me
So each gives twice and that is pleasant
To get the truly wanted present.
And there's a lot of truth in that. If you would like a practical gift, then you'll tend to give them.