I regularly come across colorist bloopers that make me question if they've really read the product - a background character's hair color changing from one from to another, or even parts of a main character's costume, colors which clash with those mentioned in the narrative, etc. One has to wonder sometime if anybody sits down and reads a comic cover to cover once it's complete, but before it's published.
I suppose these bloopers should be slightly more forgivable if the product was originally B&W and is being recolored for a new release. At least in this case, there's no reason to expect a close scrutiny of every page by the original artist(s). It can be frustrating, however, if the blooper appears to be the result of sheer laziness.
Consider for example the recent single volume rerelease of Brian Michael Bendis' (1999/2000) true Hollywood stories comic, Fortune and Glory.
Much of the story revolves around the endless hell of waiting rooms and pitch meetings which drives the business of Hollywood. As such, repetition in both images and story elements drives much of the humor of the exposé. Unfortunately, the gag on this particular page is sullied by the laziness of the colorist:
Not all the details of the art come across in this scan—in particular, the main character (our little bald friend)'s eyes are shifting back and forth in every frame. Then, in the final full panel on the page, the eccentric holding his pen in the air briefly puts his arm down for a rest. This nuance seems to have been lost on the colorist, who clearly just pasted the exact same colors onto this panel as the previous ones.
The finished product, however, is obviously f-d up—surely once the colors and inks were merged, only a quick glance (or the glance of an actual reader) was needed to spot the error?