The line is in custom games, where you can test all you want. generally you'll explore different features during normal games, and if you find something that conflicts, you'll get a custom started and try to reproduce the problem. If you can reproduce the issue semi-reliably, you post on the forums about the bug/glitch and ask people to confirm it with you, or by themselves in a custom.
I know this doesn't explain it too well, but the best way I can is to say don't buy something ineffective towards winning on other players time, it's almost guaranteed to royally disrupt someones cool.
~Summoner namora, of the lower case.