I'll ping /u/tiako as a guy that is generally good with archaeology, but I can pull a bit from my classical history textbook.

Heinrich Schliemann gets the credit for discovering the ruins of Troy. He was perhaps the archetypal European treasure hunter/colonist/archaeologist. This means that its easy to look down our modern noses at Schliemann for a few reasons.

1) Extractive colonialism: Modern archaeologists are generally concerned with respecting the countries and people that have a claim to excavated artifacts. Objects dug out of a tomb in Egypt are thus more likely to stay in Egypt, or at least be owned by Egyptian cultural institutions. Schilemann and his ilk generally assumed that the treasures they pulled from the ground would be wasted on the backwards brown primitives that both descended from their research subjects and did most of the manual labor on dig sites. These men helped turn the European museum scene into a series of glorified trophy rooms for showcasing plundered objects.

2) Fabulism: As the original thread pointed out, Schliemann promoted objects that he found as belonging to characters from The Illiad (and apparently sincerely believed as much), despite having no evidence other than "this stuff is nice" and "I found it in kinda the right place." The mythology he helped created around these objects remains difficult to dispel.

3) Destructive digging practices: Sure, Schliemann dug up a lot of cool stuff. In the process, he and his crews tore through earlier layers of artifacts to get to the "good stuff," and paid no attention to more subtle features like soil stains.

Schliemann was a particularly bombastic example of archaeologists of his time: amateurish, uncritically assumptive of white supremacy, and only interested in big finds. Given the popularity of Indiana Jones in pop culture, this is still the assumption of many people when they think about archaeologists.

Source: D. Brendan Nagle, The Ancient World: A Social and Cultural History (Boston: Pearson 2014)