I have two.
First, I believe that I am the worst Pac-Man player of all time. There's just something in my brain that wasn't built for outsmarting those ghosts and getting every last one of those little pellets. I stink at it.
I also stink at Burgertime. I don't think I've ever gotten past level 2. If baffles me how people are so good at this game. You have to run over the ingredients several times and make several burgers... and I always end up having to use my pepper early.
So yeah, Pac-Man and Burgertime for me.
I'm good at a lot of other old games though, like Donkey Kong, Asteroids, etc, so it's not like I'm totally pathetic. But I want to know what old games you stunk at.