It depends on a host of things, like ferment temps, type of yeast, IBUs, length of time sitting, etc etc. Generally, you want to harvest from lower-IBU beers that have an OG of 1.060 or less. Even so, you can harvest yeast from most anything if you give it enough time and TLC.
"I can't believe how many people think Air Lock is pronounced Hydrometer." -BigKahuna
"If you gave me a beer with placenta in it without telling me I would kick you in the nuts." -ODaniel
"We be in a big hurry for dope beer with much alcamahol and flavor, quality, balance, and aroma don't matter. We just wantz to be druck, u know?" -Yooper