On this week I noticed that if I - a tester - check some functionality with a lot of bugs in it and ping-ponging these bugs to developer several times (some developers can't fix bugs with one version), then with another "fix" I am more likely to be critical on code, not on myself. That means that I am more likely to report every suspicious thing about that functionality, even if it is not a bug.
Testers mistakes in that case are mistakes, that developer can't fix in code: wrong settings, for example; or wrong data; or misinterpretation of documentation.
If developer produces relatively clean code, I assume that if I find suspicious behavior it more likely to be my mistake (because I know, that this developer makes few mistakes). Or, in another words, the cleaner code usually is - the higher probability that founded bug is caused by tester.
This kind of prejudice is not productive, so every time I try to "reset default settings" and don't think about developer, who implemented the task, but think only about code and implementation. I even preferred to check anonymous tasks (without developer's or analytic's name), but unfortunately I can't do it in JIRA.