I think true masochism depends on the level and the type of pain you enjoy. I laughingly call myself a real masochist because I double majored in history and english, two of the most boring droll subjects to most people. (Not to me but...hello masochist).
I enjoy physically pushing myself to my limits but there are certain pains that I won't even feel remotely comfortable attempting. Burns are right out to lunch. However I've done the self inflicted pain, such as scapels and knives, particularly at emotional low points. I think at times masochism is a type of drug to help you overcome and kick start yourself from those times in which you may otherwise desire to curl up and die.
However sexual masochism and being a pain slut, is different for me than actual masochism. I embrace actual physical pain (not just what I consider sexual foreplay) when I'm at the lowest point I can be. I think for myself it keeps me balanced, like I have the ability to hurt myself but I won't take my own life (if that makes sense?). However since my Sir came into my life, I've turned over that to Him, so if I have the need to punish myself to the extremes I will/have, I can go to Him and He helps me rationalize it and then gives me the pain I actually deserve (instead of what level I may feel...wrongly in a lot of cases...I've earned).

As an aside I really hope this makes sense...my brain's slowly dying with the hour.