Exactly!
Ask a server admin if you can test, we can be incredibly helpful if you are doing legitimate research. You won't always get a yes as there may be a good game going on, but not always.
If you are found to be testing and you have not informed any admins, you cannot blame them for taking action, up to and including an instant permaban. If you are known to cheat, do not be surprised if action is taken even though you may not have done anything at that moment, up to and including a permaban.
That you would join a game and not cheat is expected. Requiring servers to ask you not to cheat is counter-intuitive and I'm not sure why you would expect it to work that way.