I think a lot of that "buzzing" comes from grounding issues and inadequate power. Most shitholes I've lived in were built back when the toaster oven and clock radio were the most taxing electronic equipment a household would need. I recently put all my effects into a chain on a Furman pedal board, which comes with a power conditioner. I plug my amp into that and presto... that ground buzz disappeared. When we were recording my bass player was having the same problem... plugged that sucker in... hey presto!
Unfortunately power conditioners are expensive. But, a must have for live acts, I think, especially when playing in small, shitty clubs and bars. Who knows what they got behind that one outlet with six power surges daisy-chained off of it.
Of course, each buzz is a different beast. This may not be your problem. Just a suggestion.