Rather than chara, it is chara chara "frivolous" and "talkative" which are most defining. It is something that you know when seen, but difficult to define. So I referred to the Wikipedia article on it. It gives several defining characteristics, which seem appropriate:
salon-tanned skin
brown or blonde-tanned hair
always hitting on girls (nanpa)
always going to random dinner dates (gōkon)
wears various accessories
from a girls perspective, charao are: easy to talk with, fun, easy to be with; however, likely to cheat
Men who are like this are charai.