It's a really thought provoking question. I suppose none of the ratings underneath our avatars mean anything at all because we award them to ourselves. If it was a vote by other members of the forum as to who was a EN, AH or SH then it would mean something more difinitive, but as it stands I think the acronyms are just there so people can get a VERY rough idea what sort of magician you are.
For instance I'd probably take advice to heart more from a WP than an EN, not that it's necessarily correct as others have pointed out - there are a lot of professionals out there who are utterly [fill in your own blank].
It's got me thinking about AH/SH, actually. I suppose anyone can accurately describe themselves as a skilled hobbyist - since the ability to merely shuffle a deck smoothly is a "skill" - I find very few spectators can shuffle well. Walking and talking are skills, if you want to get really pedantic.
The only acronym that can't be disputed is the WP one. You're either regularly getting paid to perform magic or you're not. The rest are just abbraviations we award to ourselves based on our own confidence, arrogance or over-estimation.
