This is probably the one question every therapist gets asked. It's actually not so easy to answer. Mainly because the person never really believes what the therapist says. "Come on, you've seen a lot of bad knots, but mine are the worst.. right??"
Whenever I am working on someone new, I wait to hear this question. Usually happens as soon as I'm one minute into upper back work. I always say the same thing- "It's no more than what I expected to find after hearing what you use your back fro all day." Mostly, this satisfies some- but others are in a wild competition with other knotted backs they haven't even met. I love this, but really- it's comparing apples to oranges.
Of course the person who works lifting glass all day long for 30 years will have different aches and knots than someone caring for and picking up children all day long. Neither job is any less important than the other, it's just- different. There are 6'5" men I work on who can't handle the kind of deep [pressure I give to a 5'6" 120 lb. woman. Everyone is different. We sleep differently, we walk differently (and don't get me STARTED on the importance of good Chiropractic work!), we exercise differently and we all work differently. Even if you are the person lifting train cabs all day long with your bare hands, your back pain is not "the worst ever"- if you're able to walk and lift and sit and sleep, your back and muscles are probably pretty damn good for what you are doing with it!
We all have our own pains and aches. That's why we get massage- or acupuncture, or chiropractic work. Chances are great that your massage therapist has back pain too.
Probably not the worst you've seen, but definitely in the top 5.