Jeff may get this, but only because he's an expert.
Your partner opens 1H, RHO overcalls 1 Spade and you hold
Jxx
Axx
xx
Q9xxx
Whatever do you do? How do I know that this is a tough bidding problem? Because my online partner, who clearly identified himself an advanced player, got it wrong. Did he support hearts? Oh no, he did not. He bid 2 clubs
I can portray myself as a basketweaving expert, or Le Bron James, or whatnot online, and nobody can dispute me. You can fudge a little here and there on bridge, but really, if you claim "Advanced" then I hope that you can at least keep up the appearance for two hands. His first hand, with two points, he played well. And although his bidding didn't turn out so well (failing to double blackwood bid for the setting lead), I can totally sympathize. In a sane world I'd claim "intermediate," but given that I can find my Merrimac coups mere seconds after I play the wrong card, I feel I'm entitled...
(That prior hand saw an "Expert" open 1NT see his partner bid a game without expressing slam interest. Said expert invoked blackwood and found his partner with a perfect 13 count that could have splintered.)
Update -- And because Jeff may ask, I opened in second seat, not 3rd.
Ekted, you may be misreading the hand. With 7 HCP, unexciting shape, and only three cards in Hearts, a bid of 4 Hearts is a huge gamble. It's simply not the right sort of hand for that action. Change two of the Spades to Hearts and then it's a fine bid.
Even with the overcall, Andy, 2 Clubs shows at least an invitational hand (10+ points).
It doesn't matter if partner is in third seat. You can't be afraid to bid in case partner might be joking. If he is, and you get in trouble, that's just too bad. He risked a disaster to gain on other hands; you have to live with the paybacks. Or if it happens too often, perhaps he ought to adjust his sense of humor.
Being that they are self-ratings, they are, of course, usually optimistic. Even if a player's ego didn't encourage him to choose a level higher than others might choose, it's in a player's best interest simply to lie in order to get better partners. Furthermore, since there are no hard guidelines about accomplishments associated with each level, it usually doesn't take much to convince oneself one belongs in the next higher category.
Is there a solution? When OKB was more or less the only game in town, it used an ELO-like rating system and encouraged players to keep their ratings public. (They still do, I believe, btw.) That worked OK, but it also caused snobbery and encouraged cheating. The powers-that-be at OKB also encouraged players to list their ACBL or other sponsoring organization rating. We all know those are far from perfect, but they do help with ballpark evaluation. BBO (Bridge Base Online) has chosen to stick mostly with self-ratings, probably for the reasons above.
Ought there be a solution? I suspect most enjoy rating themselves positively. Players who over time are unable to raise their posted level may get frustrated and leave. Some players may be embarrassed by a low automatically produced score. Such ratings are an incentive to cheat or misbehave. All in all, it's a tough call, and I understand why BBO chose as they did.
I can, however, understand your (Brian's) frustration not being able to adjust your expectations about a partner. On the other hand, it typically only takes a hand or two to figure out that partner is a moron (technical bridge term actually meaning "any other player"), so it's not a huge loss not to know it a few minutes earlier.