Here via daily_snitch, and I definitely think that if people feel the burning need to leave criticism for a fic, they should at least wait until the author posts it to their own journal.

I think it's inappropriate to point out flaws in gifts, especially anonmyous ones. If your friend got a new pink miniskirt for Christmas, you'd never say, "Boy, I'm glad I didn't get that - I'd look terrible, and look at the design! It's shocking!" In the same way, I feel it's inappropriate to say "Bottom!Harry didn't work for me, and I feel you had some major plot flaws..." Well, it wasn't actually written for you, it was written for a recipient who requested very specific things, some of which may have been difficult to work around. Almost like a tailored suit - there's no point pointing out how it would never fit your measurements because, well, it wasn't made for your measurements.

I'm not someone who's against constructive criticism - in fact, in that no-so-recent wank, I was all for it. But there's a time and a place, and anonymous gift exchanges are not one of them. Especially because, if the author is anything like me, and they've worked their arses off to please their recipient, they really don't want to hear from people who didn't find it to their liking. Move on, and be glad the recipient got what they wanted. Go chase down the author and offer some con crit once you find out who it is, if you must - but don't be tainting the spirit of SmutChristmas! :)