Frankly I think the TS's observation comes from being primarily an MMA fan like myself. I don't follow boxing nearly as much, but I understand what you're saying. A guy you see fight on ESPN friday night might have a 17-0 record. In MMA, if you have a guy who's 17-0, he's a bona fide superstar, it's rare that you see an undefeated record that high. Conversely, GSP fought Hughes for the WW title the first time when he was like 7-0 or something, and in the boxing world I doubt we'd ever see a 7-0 boxer contending for a legitimate world title.
So bickering aside, I think we can all admit there's a disparity in records between the two sports for fighters that are at the same level in their respective sports. That might lead a MMA fan to think that a boxer's record is padded or something to that extent.
I don't think that's the case, I just think there's a deeper pool of challengers in boxing, when you consider that it's really worldwide. Like I said, if a guy is 17-0 and in the UFC he's either a champ or fighting for the title in his next fight. But in boxing, there's probably a bunch of guys with good records like that. They can't all fight for the title, so they fight other quality guys and the ones who end up challenging for titles usually are proven against tough competition. Look at any good boxer's record and you can clearly see that the quality of competition increases gradually as the fighter keeps winning, just as in MMA. But a boxer increases his competition more gradually, either because there's more guys to face, or something to that extent.
Just my thoughts. Please, someone correct me if I'm totally off base.