I agree. Freelance DMing is really the only way I can do it, as I have almost no prep time in which to sit at a table and put pen to paper as a "set in stone" path. So what do I do? I think up ideas on my way home from work or school, and let my mind think of where those could lead. Out of all the possibilities I can consider in that time, I use maybe three or four and pretty much let the players run the campaign whatever way they want (my primary campaign's players are all blowing their loot from their last campaign arc on a "vacation" of sorts...it feels more like a "mini-retirement", though...)
But, I digress. CHEATERS. Oh boy. I have had to deal with two in my time (both roll-augmenters). Both times I allowed their cheating to go unconfronted, but similarly ramped up the die rolls for their opposition while keeping it at the original level for the others. I think it worked.