I was talking about this to someone behind the bar once, and he also said that the reason they chose a pint glass over some other icon was that it made people more willing to buy a drink while watching the game. They'd occasionally glance at the pint glass and think "better have a pint".
Not sure whether this is true or not, but it wouldn't surprise me if it had this effect. It'd be interesting if someone else had heard this, or knew whether this was true.
Probably balls, to be honest, as while priming is a very real thing, the very real pint glasses inevitably within your field of vision are probably a far greater primer than an icon of one in the corner in the screen - so if there is any effect, it'd be very marginal.
Not sure whether this is true or not, but it wouldn't surprise me if it had this effect. It'd be interesting if someone else had heard this, or knew whether this was true.