[denethorthefirst]

I do not think that there were "evil" Dwarves in Middle-Earth. We have to remember that the recorded history of Middle-Earth has largely an elvish perspective and from an elven point of view the Dwarves may seem sometimes "evil". The Dwarves are very strong-willed, pragmatic, not easily cowed or impressed and they protect their interests fiercely and aggressive; their way of life is also antithetical to a lot of (sindarin/silvan) elven practices (mining, industry, resource-extraction, etc.). It is no wonder then that the Elves would deem them somewhat "evil" or "wicked".

But another, more important point, is that the Dwarves simply have to be pragmatic and realist in their (political) approach to life in Middle-Earth. They can't flee to Valinor to Valar daddy and mommy if things get dicey. They are bound to Middle-Earth come what may and so are forced to make hard choices and compromises simply to survive! They are not immortal, they have no valinorean "safety ticket" or strength in numbers like the humans. The Dwarves simply can't afford to always take the moral high road like the Elves! So they make a deal with some orcish tribe thats in the way of a trade route OR they, surrounded by orcish tribes in the Misty Mountains, make an alliance with one of the tribes to improve their geopolitical position and make use of the orcish infighting OR they pay some tribute to Sauron in order to stay in his good graces OR they don't immediately rebuke a Messenger from Mordor (like Kind Dain in 3018) but instead ask for more time to think, and so on and so on. Thats a cautious, realist, diplomatic approach towards the cold, hard political reality of Middle-Earth It doesn't mean that they are "evil", they simply follow political necessities in order to survive as a rather small nation amidst a sea of enemies.

Tolkien is quite clear that, aside from those forced practical arrangements, that the Dwarves were never corrupted, i.e. they never became "evil". In the "Unfinished Tales, History of Galadriel and Celeborn" he wrote about the War of the Elves and Sauron:

"In black anger he (Sauron) turned back to battle; and bearing as a banner Celebrimbors body hung upon a pole, shot through with Orc-arrows, he turned upon the forces of Elrond. Elrond had gathered such few of the Elves of Eregion as had escaped, but he had no force to withstand the onset. He would indeed have been overwhelmed had not Saurons host been attacked in the rear; for Durin sent out a force of Dwarves from Khazad-Dum, and with them came Elves of Lorinand led by Amroth. Elrond was able to extricate himself, but he was forced away northwards ... and (Sauron) turned upon the Dwarves ... whom he drove back; but the gates of Moria were shut, and he could not enter. Ever afterwards Moria had Saurons hate, and all the Orcs were commanded to harry Dwarves whenever they might."

This is a bit contradictory; by "harry Dwarves" Tolkien probably meant "Dwarves of Durins Folk" because Sauron gave away rings to the other clans afterwards so he at least tried to subdue them "diplomatically" at first. Of course that failed, and the hatred he felt for Durins Folk must have been extended to all the other Dwarves as well.
We know that by the End of the Third Age he had recaptured 3 of the 7 Rings (probably through war): so its only logical to assume that at least by the time of the Third Age the relationship between Sauron and the rest of the Dwarven Clans was as broken as that between Sauron and Durins Folk. The fact that the Dwarves of ALL Seven Houses fought a massive war of annihilation against the Orcs of the Misty Mountains from III 2793-2999 is further proof that at least by the time of the late Third Age Sauron had absolutely no control over the Dwarves because the Annihilation of the Orcs of the Misty Mountains is clearly not in his interest.
Because of the close relationship between Eregion and Khazad-Dum the Dwarves of Moria also probably knew of the danger of their Ring and (just like the Elves) never wore it during the Second Age while Sauron had the One (so even IF the Dwarves of Moria could somehow be dominated through their ring, Sauron would not have been able to achieve that because they refused to wear it). And maybe they passed their knowledge on to the other Houses (i think thats rather likely).

Another Quote from "The Silmarillion", Chapter "Of the Rings of Power":

"The Dwarves indeed proved tough and hard to tame; they ill endure the domination of others, and the thoughts of their hearts are hard to fathom, nor can they be turned to shadows. They used their rings only for the getting of wealth; but wrath and an overmastering greed of gold were kindled in their hearts, of wich evil enough after came to the profit of Sauron."

So Sauron failed to directly dominate the Dwarves, he only profited indirectly. Maybe this wrath lead to infighting, or it was this greed that pushed the dwarves to dig ever deeper for mithril (and awaken/release the Balrog) and maybe this greed also lead to the massive wealth of Erebor that eventually attracted Smaug.
But while the Dwarven Rings indirectly lead to evil, the Dwarves certainly did not bow to Sauron or became his servants, they are just too stubborn and proud for that.

Another Quote from the same Chapter about the Battle of Dagorlad:

"Of the Dwarves few fought upon either side; but the kindred of Durin of Moria fought against Sauron."

Even IF (big if) Sauron dominated the eastern Houses of the Dwarves during the Second Age, how come so few were willing to fight for him? I guess those few were either mercenaries/specialists that Sauron paid or small detachments sent for the aforementioned political/diplomatic reasons, a symbolic token gesture maybe. I dont think that those Dwarves fought "under" Sauron (like the Orcs and Men) but more "alongside" him. I find it hard to believe that they gave up their religion, worship of Mahal the Maker, and accepted Sauron as God-King.

Again: the Dwarves cant always take the moral high road of the Elves because they are not immortal and dont have a valinorean "safety ticket" that would allow them to fall back on the Valar. They have to live, stay and die in Middle-earth and are forced to compromise and make hard choices. That is not "evil" thats life! The Elves just don't "get it". Being totally "moral" is easy if you are immortal and can always flee the situation and leave for an otherworldly paradise!