I think that IDW has a quality control problem with not enough editors and too many books, comics, and other media that they have to pay attention to. While their original comics that win awards are pristine and perfect, their franchise comics are rife with errors, both grammatically and artistically. Sometimes, it seems like, "Hey, wouldn't things be simpler to just make sure these things stop happening before they get released so that you don't have to worry about them later?" but sadly, no, they keep happening. I blame too many artists and not enough editors. Mistakes can happen and do happen to every publisher, but that's no excuse. I mean, DarkHorse was two seconds away from releasing the only solo Spike cover it had for S8 with a brown-eyed Spike. His blue eyes are sorta iconic to his look, but Jenny Frison really thought they were brown. Promo images got released, fans went batshit on the DH forums about the mistake, and it was corrected, but I'm guessing that some already printed copies had to be pulled and replaced before shipping.

Another problem for both DH and IDW- neither company does full maquettes of the main characters nor do they have consistent style guides or design sheets. Buffy's hair is not piss-yellow. Buffy's eyes aren't really bright olive green. Spike's eyes are blue. Spike is not right-handed. Franchise comics just don't get the same kind of care that they probably deserve.

Of course, mistakes like this also happen on the show. In TGIQ, Angel described Buffy as being "blonde, blue-eyed." Allow me to quote Cordelia, "My eyes are hazel, Helen Keller." XD