Dislike:
Double Pulls.
Under 3.125 ~ 3.25 inch closed.
Super thin mark side to pile side.
For the most part, single blade slipjoints.
I'll make exceptions for special purpose knives such as pruners and Marlin Spikes. (would it killum to put at least a pen or coping blade in them?!?) I prefer at least two different blade profiles, or a blade and a tool.
Hard/Stiff pulls. I don't want or need to fight with my knife to open it, even if my hands arn't wet/cold. As for using a "steel fingernail" or pliers/vice grips to open a blade ... no thanks. Just more to carry.
Besides, I have plenty of knives with a reasonable pull in the patterns I like that I don't need to tote one that needs a tool to open.
Excessive blade play.
Shallow nail nicks. (fortunately I have a faux Dremel and can fix that)
Blade rub that affects the functionality.
Celluloid (Please pardon my language) covers on a new knife.
No excuse for that. Acrylics can look the same and will never outgas.
Mirror polished fingerprint and smudge magnet blades and bolsters.
Gaudy covers.
Oversize shields.
Prefer:
Carbon Steel Blades, with carbon steel backsprings.
Brass, Bronze, Copper, or Steel bolsters.
3.625 ~ 4.625 inch closed for pocket carry.
Thin edges, with an acute edge angle.
The blades can be sharpened in the field with a smooth rock if I misplaced/lost or forgot my sharpening stone.
2 hand opening. No nail nick on blades that can be pinched open.
Something that is unlikely to be confused with/for a "weapon" by Mr. and Ms. Gertrude Mae Publik, and/or the local Constable, or Polly Tishunn.
Depending on the pattern, a shackle for a lanyard.
Durable covers.