"Dwarfs see themeselves as masters at the forge, construction, sculpture, engineering and many other arts. They can usually tell when they encounter something made by a people other than dwarfs and waste little time in pointing out its flaws. The works of others rarely meet their approval, and almost never garners their praise, as they will always find something wrong with it, even if they have to invent it"
Now, given the context of that snippet (dwarf egos/cursed pride), one could argue that this just means they'll trash-talk everything while actually still respecting/wanting to have it.
This is of course combined with the constant thought of their ancestors watching over them, so they strive to act "honorably" in all things, lest they bring shame to their entire clan... Exactly what is "honorable" to a dwarf is a bit hazy, as they won't stoop to stealing but are apparently just fine with completely fleecing someone in a contract if the other party doesn't read the really fine print. I'm not sure where lying falls in that calculation.
"Being suspicious and untrusting means dwarfs do not enter into bargains lightly. Even among their own kind, they require more than an oath and a handshake. For any transaction that involves riches, dwarfs draw up elaborate contracts that might run dozens of pages in length, filled with convoluted language that shifts the risk to the other party while offering the dwarf the best protections. Of course, dwarfs are wise to such contractual tricks, and negotiations between dwarfs can be fierce and last several days before they can reach terms. For those unfamiliar with the way dwarfs do business, signing a contract whipped up by a dwarf is a quick way to lose one's shirt."
The "any transaction that involves riches" is a real sticker, depending on your definition of "riches". Considering the Gold Lust madness for dwarfs (which is fairly debilitating, I might add) is invoked for "any item worth 1gc or more", what does that mean for the definition of 'riches'? I suppose that does answer the question of them seeing value in things not made by dwarfs, but that is also explained as being an attachment to the rare metals and materials used to make the items, rather than any competency on the part of the crafter.
Also, in addition to being suspicious and wary of everyone, they are violently hostile towards two of the player races, specifically distrustful towards two more, and just generally disdainful to humans. Clockworks are fascinating (although they'd never admit as much), but not to be considered as thinking beings.
"Gruff, critical, and suspicious, dwarfs make few friends outside their own kind. They covet treasure but temper their greed with the certainty their ancestors are always watching. Thus, dwarfs conduct themselves with honor to avoid bringing shame to their clans."
Plus some more yadda yadda suspicious racists yadda yadda no friends yadda yadda wars started over perceived insults etc.
I dunno, I suppose one could argue that the other races are bestial and unthinking enough that "lying" isn't really a concept when dealing with them, therefore it's not dishonorable? Become meta-racist to the point where you can actually get along with people by spitting through your teeth?
Still doesn't really solve the adventuring problem though... While a farmer may venture out with the herd to find better grazing for a richer beef, he's not likely to do so if he suspects the herd might stomp on him at any moment. Better to just keep a safe distance and let them sort themselves out in that case, which means from a practical standpoint that you're gonna be kind of a shitty party member to deal with.