Here is a fan page devoted to Banastre Tarleton: http://home.golden.net/~marg/bansite/_entry.html
Stories and myths about Tarleton abound. My favorite absurd story is that he dug up the grave of a recently deceased rebel because he wanted to look upon a "great man." That is wrong on just so many levels and makes no sense at all.
Bass reported that he and his men once passed themselves off as rebels (this sort of thing happened a lot in the South) went to a suspected rebel town where they were wined and dined, and then at the end of the party they arrested all the rebel leaders. That fits Tarleton's character. He was young, daring, and brash. It isn't hard for me to see his men getting carried away at the Waxhews and him maybe being negligent at stopping the carnage.
The Waxhews is an interesting incident. The American General Buford was retreating and Tarleton was ordered to hunt him down and destroy his command. Tarleton's Legion pursued with an infantry man riding with every dragoon. Tarleton was outnumbered, but sent a grand demand to Buford to the effect of "surrender immediately or be cut to pieces." Buford responded "we will fight to the last extremity." Tarleton ordered a headlong charge. Buford had given his men orders to the effect of don't fire until they are close enought to see the white's of their eyes. That may work with infantry, but not cavalry at the full gallup. The rebels were being cut up almost before they could get a shot in.