Well, some of those easy definitions:
"Professional" - plays as primary source of income
"Recreational" - does not
"Serious" - Has no fun :joker:
You know, there's nothing really dangerous about practicing continuously. I mean, it might be kind of obsessive-compulsive, but not more than constantly ironing your underwear. It's basically harmless.
But if you've got somebody playing
a lot, how does an outsider tell the difference between a compulsive gambler and a hard-working AP? I can think of two "tests":
1) Is the player actually playing in such a way as to ensure a long-term advantage? You'd have to test or observe the player's technical proficiency here. If they fail this test, they are, at best a failed advantage player (which technically isn't an advantage player any more)
2)
Why is the player playing? If they're playing primarily for the excitement of the win and the... whatever, of the loss, then they're a gambler. If they're just playing to grind out an eventual profit, they're an AP
But 2) is where everything gets murky. Everyone gets excited if they win a lot, and bummed if they lose. And there can be such things as compulsive gambler card-counters. Where was the article? Ah yes:
http://www.blackjackforumonline.com/content/professional_compulsive_gamblers.htm