I think you can get away with some terrible sounds as long as you keep them within the realm of something a real bull can do a place it would do them, what ruins the hunting for everyone in an area isn't someone sounding like a sick spike, it's the guy who you can hear extend his pack bugle first, that plasticky BRRRRRRRIP is like nothing in the woods and a dead tip-off that something isn't right, same with zippers, plastic boxes holding reeds, velcro, beating a plastic bugle tube against trees, mega challenge bugles out of the blue for no reason, any noise an elk can't physically make, and so many other things hunters do... if you keep it to a simple couple note locator bugle you can be pretty bad and not spook elk...
the other thing is the where, if you combine a bad call with being 50' from a truck that shut off 1 minute ago it doesn't take all that smart of a bull to put it together, same with 20 bugles from the exact same spot while you glass or eat lunch, if you can't think of a reason a real bull would be standing where you are bugling and bugling as much as you are then don't bugle... again if you are in a place where a real bull would be doing what you are doing you can get away with some pretty questionable noises, it's as much about context as the actual noise I think...