I rarely have gas and the smell isn't any different than I had before surgery. I have spoken to a few people that say they have worse and more smelly than before surgery. Probionics seems to help when that happens.
I think this may be related to the artificial sweetners people eat after surgery - aspartame gives me terrible, painful, stinky gas. I don't think the smell of gas is affected by the surgery itself, but its normal to be a bit gassy for a few weeks or months afterward.