Hehe, I really like this.
I check x360a every time when I get a new game or when I want to look up for some achievement/game information (obviously).
When I came to L4D a month ago I was like: there are so many threads busy with discussing glitchy achievements! I have been playing L4D mostly every day recently I haven't found any glitches with achievements, what so ever.
Of course, I was wary of the glitchy achievements and how to avoid/(''fix'') them. Chaos Generator and the Expert achievements left!