Okee....

When I'm testing a Battle/CTF/Race/etc pack, I usually use jjnxt to get to the next level after looking through one a lot. This is not cheating, it just takes less time then exiting and bringing up the next one each time.

In Single Player, I get stuck sometimes. This means I either use plain JJfly (Hold down down while in the ground with indefinite helicopter ears and you go up) or JJfly+JJnowalls to get out. This is better then JJK, so I don't think it's really cheating either.

In Tomb Rabbit I use JJInv. I'm not ashamed to admit it. I do aknowledge this as cheating.

Sometimes, when working on my own levels, I use JJFly and JJNowalls to get ahead to the latest point I'm working on. This is as an alternative for just moving the start position. Again, this probably doesn't really count as cheating.

I sometimes use JJAmmo while working on my own levels, to get toaster for frozen springs for example.

And, of course, once I'm totally done testing things, it's fun to put on a fire/bubble/plasma/laser shield and go around decimating everything!