"Tea parties" were originally constitutionalist, fiscal-conservative gatherings dominated by libertarians.
At least that's how it was in Boston and in Seattle. Two places I am most familiar with. (The first-ever "tea party" was held here, in the Emerald City, on Feb 16, 2009. Keli Carender was the organizer).
The central premise of the tea parties (and the prime source of their relative success) was: we, conservatives, libertarians and moderates now (having been shaked out of complacency by the Crisis) come together to promote candidates who would do better than the alternatives, when it comes to fiscal responsibility, pro-free-market policies and individual rights. And - we declare truce on the fronts of our disagreements ("social issues", immigration, etc).
Yes, from the beginning it was a populist movement (instantly dumbed-down from its "Ron Paul Revoluton" predecessor). But: It did produce Chris Christie, Rand Paul, Justin Amash, Nikki Haley, Mike Lee, et al. They are the best the GOP has to offer. This is a fairly faint praise, but yes - "better" - much better -than "the alternatives". From my, moderate-libertarian point of view.
Of course, nothing fails like success. When it became clear that "tea-party-ism" means more votes and better publicity, a whole bunch of perfectly statist demagogues jumped on the bandwagon. The "bachmannisation" is a real thing, and it is not pretty. But I think the core of the tea-party movement is still healthy - as healthy as anything populist can be in principle.