I have never had a sour pipe. I mostly just run pipe cleaners through, and after I've dumped the ashes I clean out the bowl with a rolled paper towel, and make sure I rest it with the stem elevated. Every so often, I disassemble and hit the the works with Everclear, Qtips, bristle cleaners, paper towels etc.
I've only met one piper who said he had sour pipes, and he complained about all his pipes being sour (he was a a guest at my motel). When he smoked, he would smoke 3/4 of the bowl, then fill fresh tobacco on top and light the top.....and would do that repeatedly. I never saw him use a cleaner and he had so much carbon buildup the chamber wasn't much wider than the pipe tamper. I think as long as you use a modicum of care, you'll keep the funk at bay.