But those same relatives could also feel "grateful" for what Washington did for the eventual freedom of blacks in America.
Their ancestor could have easily been a slave to some slave holder that fought to perpetuate slavery forever rather than Washington who for whatever the motives actually led the army that would establsih the government that would eventually free slaves less than 100 years later.
I doubt most decendents of slaves thinks of George Washington as a evil man. As a matter of fact at least 1 slave family thought enough of George Washington to name their son George Washington Carver...
I do think time is sorta relative to deciding whether someone was evil or not as the interpretation at the time is based on what we are experiencing ourselves...I guess this is your point that whatever we as individuals feel determines our reality, but the "real world" acts and reacts as a collection of all the independent realities. WTF am I talking about..