Coming in late on this thread, but what the hell.
Gimmick? Those Ovation people are pretty good gimmick-mongers to fool so many people for almost 50 years.
I bought my first Ovation in 1971 and have owned them on and off ever since, along with many other brands of acoustic. I've formed the opinion that people single them out for slamming because they are so easily recognizable, and because the low-end ones ARE terrible, just like they are with any brand (think Squire Bullet series).
Unfortunately, all you ever see — and therefore all most people ever get to play — at GC and other music stores are Ovation's cheap, foreign-made Celebrity and Applause series. Not much of a yardstick, and it could be easy to form a negative opinion of the whole brand after a session with one of these.
However, if you were a total newbie and you plunked around on a few low-end Epiphones and Sigmas, you could easily form the same opinions about Gibson and Martin guitars.
However, if you play the high-end, USA-made Ovations (Legends, Adamas, etc.), you will really appreciate how good they can sound. I have played a lot of different guitars over the years and always seem to come back to Ovation. For the money, you can't beat them. And I'm talking hundreds, not thousands, of dollars. The 1778T Elite shown earlier in this thread is/was an $800 guitar new. A good example sounds better than a LOT of much more expensive guitars, including Taylors and Martins.
Like any guitar, a room full of Ovations of a specific model will all sound a bit different. There will be one or two that sound dead, and one or two that will sound wonderful. And contrary to popular opinion, they do sound better with age. I still have one I bought new in 1971 and it sounds much better now than it did then.
I do admit that I detest that stupid plastic thing they put around the soundhole on center-hole Ovations. It makes them look like carnival prizes. But the bowl? I have no problems with it "slipping" any worse than any other guitar. Maybe those having this problem have "deep bowls" themselves?
Here's Nancy Wilson, who used to open Crazy On You with this Ovation Legend. (Heart - Crazy On You - Ann & Nancy Wilson Live 1978 - YouTube
) Other proponents, as mentioned, have included Melissa Ethridge, Al DiMeola and Glen Campbell. I doubt if any of them feel duped by a gimmick.
Fender bought Ovation a couple or three years ago and now almost the entire line is manufactured overseas. (Adamas are still made in the US). I hear most of the Hartford plant is now given over to building Gretsch guitars, which Fender also owns. Ovation forums have lamented the changes, although some who have tried the newer Legend and Elite models say that while some of the construction processes have been "streamlined", the mid- and high-end guitars still sound good.
So hate 'em if you want. Lots of people do. Or have an open mind and try a bit of everything. Like some people here, you might horrify yourself by one day play an "O" that you actually like.