If loot is truly random, then any particular category of character builds should get the same amount of suitable equipment generated as any other, with the remainder sellable. Due to design choices or balancing issues there may be a bias towards or against certain attributes, but that should not effect general equipment classes (I have not seen any complaints in the forum about that, anyway).
Part of the problem is perception. Good stuff that you can not use stands out in your memory more than good stuff you could use but it isn't quite as good as what you have already. That, and if a game allows multiple character types, there is always going to more stuff in a game that does not suit your playstyle than does.
Playing a warrior, I've noticed that mana bonuses are higher and more common on equipment than hit point bonuses. A couple levels ago I got a +60 mana bonus on a ring from a jewelry chest. Since one of the rings I had was getting a little outdated, I decided to reload for a better one (since that particular chest obviously could have good quality items for that point in the game). I didn't get quite that high on mana again (came close), but there was a clear bias (likely for balancing) and the best hit point bonus I got on a ring was +39.
I certainly have not been hard up for usable equipment, though.
I boosted Lockpick early, and have gotten almost all of my equipment from random loot. Sometimes random loot is crappy, but the more loot you have access to, the more good stuff you are going to find. Also, I don't like leaving stuff behind.
It does kind of suck to mindread someone only to find a stash of a couple hundred gold, or something. On average though, mindreading is a benefit, as you can get good loot as well as stat and skill points that way. If every mindread was guaranteed to pay off, then it wouldn't be much of a choice.
The treasure in the bandit temple was quite disappointing, though, especially since I missed seeing the key the first time through and reloaded, thinking I may have skipped mindreading what's-his-name (it wasn't all bad, though, as I used 4 or 5 healing potions the first time though, and only 1 the second).
