I use a simple soundlab fog machine, uses non-irritatating non toxic fluid. Looks great and kids love it!
Has anyone experience on how to avoid the slippery residue it tends to leave on the floor? I've been pointing it into a corner behind my gear.

I've Never come across this problem before. it's common with bubble machines but never had it with foggers. You could try changing the brand of fog fluid that you use, and cleaning out the heat exchanger (Instructions on how to do this are on a another thread).

I had this problem last year with a smoke machine, after it started leaving this residue its heater packed up a couple of weeks later, so I dont know if the residue is a pointer to a future problem?..

Mind you even with new smoke machines , the fans on the lights & Amps , seem to get coated with sticky stuff which leads to all the dust sticking to the blades and fan cover.

Have you tried cleaning out your smoke machine, using the method explained in another post using "White" vinegar and distilled water ?