Not OP and don't have an example to hand, but something I noticed is that with subjects where I understand them well I do tend to notice a bit of a bias, but equally edits are usually accepted too.

The problem in my mind is that on subjects where I'm not as well educated I may well not notice the bias because I don't know what may or may not be disputed for a given subject matter.

Obviously everything on Wikipedia should be sourced but it's entirely possible to be selective of which sources you use.