When I bought my bike it was in what I can only describe as an "abused" condition, which resulted in me spending quite a few quid getting it up to a decent standard.
The pulsing problem I had baffled me though, but in hindsight it was all a good learning curve, albeit very irritating.
The fella who owned it before me clearly never looked after the bike, and more than likely used it as a toy, but I did get it for an appropriate price.
Alarm bells starting ringing when I changed the oil and managed to pull FOUR litres of old nastiness out of it.
Makes me wonder if the brake cable had actually taken a hit at some time before I bought it causing an internal weak spot, as you say similar to a hernia, rather than just naturally breaking down?
The horrible thing was no matter what mechanic I let have a go on the bike they would always say "warped disc" straight away but I just knew it wasn't that because I had already bought a new set and it was still the same.
That's why now when I hear people mention warped discs I try and point out it's a very expensive habit to fix, and other areas should be investigated as well before splashing out on a new set, because it's a term used rather too loosely from my own personal experience.