You guys have covered quite a bit, soIwill throw in a couple of things that I don't like.
1. wrong material for the knife. I generally don't like stone handle material. Even the really old stuff like carved jade handles on old Indian and Persian blades. One of the exceptions is I have seensome interframe folders done in Malachite that looked cool. I do NOT like turquoise spacers, etc. I guess paracord handles would fall into this category too.
2. Knife is too busy/has too much embellisment. File work maybe the worst offender. Too much is too much. Some knives fall into the category I refer to as "Early Baroque Brothel" style.
3. Clunky grinds. I don't like big thick blades with no taper and I especially dislike ones like that with partial grinds, such as a saber or scandi type grind. I no longer like the big Randall bowies for that very reason. I favor flat grinds over hollow, but don't get my wrong. A Loveless Big Bear still makes me slobber.

4. Parts out of proportion. The one that usually gets me is a guard that is too larg, too small or too thick.
5. square handles. I do like octagonal, etc handles like a coffin handle bowie or a Robbin Hudsson knife, but not the square ones.
6. Any knife that looks like a prop from a Star Trek movie, a Conan movie or claims to be highly effective at something like "covert de-animation"
6. The big one......knifes that look like they would be either impossible or difficult to use as a knife should be used. I'm not talking about knives that are too pretty or expensive, but ones that look uncomfortable. This covers everything for uber-pricey customs fantasy knives to cheapo mall ninja crapola.