I am a Chevo whore but will not buy bad game's for easy chevo's,I buy what I normally would but play it more or complete the game more then once on harder diffs for the chevo's,so with that said chevo's give game's more replay value for me by a long shot,I wouldnt have put 300+ hour's into Skyrim other wise.
The shorthand cheevo bugs me a lot. Also it's cheevo, not chevo surely.
Chevo = Ch-eh-vo
Anyway I'm very aware of achievements as I go through games these days and it certainly changes the way I play them. It's kind of annoying really, I'll care about doing boring stuff because of wanting to be completionist but I really don't like that I care. It was quite refreshing to play on my brother's PS3 over the Easter break as I had no interest in trophies - it meant that I just played the bits of games that I wanted to without wasting time grinding towards meaningless numbers.
All that said there must be some part of me that likes doing it - probably that part of my brain that wants to impress people even though I'm well aware that nobody cares. Stupid brain.