The "Beautiful Snowangel" taunt of Crystal Maiden is supposed to leave a snow angel behind for some seconds. It used to do that on the source 1 engine, but stopped doing it since the game was ported to 2. Since source 2, the snow got less and the snow angel is completely messed up. The only good thing source 2 did to the taunt was increase the duration of the "snowangel" on the ground after the taunt.

Here is a comparison between how the snowangel used to look like, and how it looks now.