With the onset of asset stores, some nasty people appear to be taking assets not belonging to them, recoloring them, and then selling for money

For example, Yar's tileset (http://pixeljoint.com/pixelart/49116.htm ) was taken and sold without crediting him:

https://www.gamedevmarket.net/member/clemanto/

In addition, Unity's store was plunder by one Russian guy (using stolen plastic card), who setup a pirate version of it, selling the same assets but only for $1 each. Luckily he advertises it mostly at Russian gamedev sites. But it is still online, after all the years. I find that appalling!

So watch out!