Here's an interview with Phil Ivey:
CD: What type of tells do you look for while you're playing?
PI: I look at the person. Getting back to my eyes, people always talk about them because I don't wear sunglasses. I figure that if you can't deal with someone looking at you, you shouldn't play poker. Suck it up. If you have tells, work on them. Some people wear sunglasses so that you can't get a read on them. That's just poker. Lots of top players don't wear sunglasses. I tried to wear sunglasses once at the World Series and misread my hand. I threw them into the garbage can, and they were $1,100 sunglasses.
(Phil's wife overheard this and said, "So, that's where those went. I thought you lost them." "Yeah," he said. "I lost them in the garbage can." "Those were nice sunglasses," she said. "Yeah, so nice that they cost me a $100,000 pot.")
//////////////////////
I don't think Phil makes that mistake if he practices reading hands with the sunglasses on. That's why I've started wearing my sunglasses when I'm playing online. Does anybody else do that?
