I cleaned things, quite well. Fixed a vacuum cleaner that the boss was sure they'd have to throw out and replace. And found out about the power of Industrial Strength Odor Counteragent (Literally, I made the dumpsters smell like NOTHING! Admittedly I used it at four times the recommended strength...).
And noticed all the nice bottles that had great big huge warning labels on them. They were all bulk purchases so didn't have all the fancy logos and colours you find with residential products, so had lots of room for them. I don't remember them any more, but I was thinking back then, "Man, do they WANT us to experiment with this stuff or not with these warning labels?"