If it's an unknown with a $200 stack I assume he's the donk. I don't play that much different against him mind you. But if it's one of those decisions where you're sitting on the fence I go with the play I'd make with a bad player.

If it's a table with a high average pot the big stack is almost the donk 100% of the time. Of course you should avoid him anyway because he is running super hot and he will easily stack you when he raises with 58o and you reraise him hard with AA and hit an A69 flop when you hold AA and he chases his gutshot and hits. But I'm not bitter about yesterday or anything...