I think there was, as with anything at any time, a spectrum of behaviour. Looters with nothing but pure profit for motivation were more the rule than the exception though, I believe.
As far as the Wetherills specifically, I think they were "the good guys" when, as just noted, their actions are taken in the context of their times. I've also read several books referencing the activities of the early "pot hunters" like the Wetherills, McCloyd, Graham etc., as well as the earliest "archaeologists" to dig the area like Moorehead.
For the most part, at least according to what I have read, the Wetherills were in large part doing what was considered to be "archaeology". Much of their digging and artifact removal was done within the framework of "expeditions" like the Hyde Exploring Expedition and the Whitmore Exploring Expedition. Explorations often mostly financed by "scientific interests". With notes and photos of the excavations done that actually set the standard of the day for how to conduct a dig. Not to mention, Richard Wetherill essentially pioneered the use of stratigraphy as used in modern archaeology to this day.
I think he did the best he could given the context of the times - with generally good intentions.
I don't think he was typical. I think the vast majority of artifacts removed in the early days were looting for fun and profit, plain, pure and simple.
- DAA