Is it just me, or are there a lot more HITs that have a minuscule initial payment (say a couple of cents) and then a large bonus at the end? I think this practice is a bit shady. Doesn't this allow requestors to entice workers for longer more involved work with no guarantee to be paid? As far as I know, bonuses don't have to be paid and are completely up to the requestor's discretion. They can approve for a couple of cents, get a ton of research, and then chose not to pay the bonus for any reason, without recourse. As far as, I know bonuses can't be disputed. They keep their approval ratings high.
Also, I don't always keep track of bonuses I was "supposed" to get, so I have no idea of how much I have left on the table. I thought bonuses were supposed to be reserved for exceptional and thoughtful work, and not as the main compensation.