success as an Idler would be based on idling. not doing anything, or at least not doing anything 'productive'.
quests could involve remaining logged in but not doing anything for long periods of time. skill points could be gathered for idling in idle friendly locations.
certain quests could involve true idling, doing absolutely nothing for hours on end - but long term success should not be hindered by walking around, talking and socializing. indeed, that could be part of the criteria for success.
a character who plays for a year, makes many friends, enjoys the game but does not advance past level 1 could be considered an "elite idler".
material wealth despite unproductiveness could also be a measure of success. players who do next to nothing, yet possess lavish homes, expensive items and many currants could also be considered elite idlers, with a secondary expertise in "mooching".
mooching could actually be a skill on the idler's skill tree. when given an item for the first time, an item the idler/moocher had no hand in producing, the person donating the item would gain XP. the moocher would gain nothing [except the item and maybe idler skill points].
one important item for an idler would be something called a 'boob tube'. possessing a boob tube, or another similar item, would cause the idler's XP to slowly depreciate, allowing them to compensate for mistakenly gained XP, and keep their XP as close to zero as possible.
idlers should have their own patron giant.