I did a starter from a saved batch of White labs irish ale yeast that I hope to use this weekend and there is a small ring right above the wort. It was pretty active, so it could be from the mini-krausen it developed during the initial fermentation, but I wanted to test it for contamination. I'm afraid if anything it might be some wild yeast contamination, so I was curious what to taste for for wild yeast? I know most of the bacterial off-flavors, but haven't heard much about wild yeast off flavors, except that they can get pretty wild.
Let me know if anyone has any input...