I always wanted to try Smashbox O-gloss and Too Faced mood swing gloss, but I never got around to it. Basically what these glosses do is turn from clear to a 'flush' color depending on your own chemistry.
You can't see it here but I squeezed some out and it comes out completely clear.
Swatched on my arm, it is clear:
I can't believe this gloss cost $2.99, it's really got a nice texture and it lasts a while. It doesn't have any scent to it. I wish it smelled like black licorice or something.
I think this is limited edition for Halloween, I might have to pick up some more!