Not sure if it was supposed to be designed this way, which wouldnt make sense to me. But when you use the Rogue Scientist skill Alchemical Toxic Canister you are given 20 experience. While insignificant, it can be abused to gain levels without trying. Not sure if it was supposed to give you experience, not necessarily a bug but not sure where it would belong.
This is known-- it happens because the skill itself works by summoning a "gas canister" monster that then dies, exploding on death. Apparently there's no way to have a 0 xp monster. I don't think it's too abusable, since the skill has a long cooldown.