They are absolutely not all dumps. But neither are $100-150/night, non-Disney motels equal to WDW Deluxe Disney hotels. I get the impression that that is what you are looking for- the Deluxe experience for the same price as in FL. DLR is in busy, very expensive SoCal. The DLR onsite hotels are so much more than WDW because of the completely different location and economy. If you want the nicer hotel experience, and you can't afford the GCH or DLH, then I'd look into a Hilton or Embassy Suites. They still won't be Disney Deluxe hotels, though.
I've stayed at many hotels over the years, some super cheap and some super expensive. When we go to Hawaii, we drop a lot of $/night and don't even blink. We want ocean front, beach access, nice pools, and a kitchen because we spend a lot of time in the room, in the pool, and on the beach. When we go to WDW, we stay value or moderate because we are in the room to sleep and get ready. For DLR, we stay offsite at a hotel that is affordable and close, for the same reason. These are not luxury hotels, but they are also not dumps. They are clean, serviceable motels that are more than suitable for their purpose.
We have stayed at Hojos (three times), Fairfield Inn (four times), Castle Inn and Suites (one time and it's not our favorite but it's fine), and now we are booked at the Annabella for our next trip. There are many others I would stay at based on this boards recommendations, but I focus on most affordable because the hotel, as long as it's close and clean, is the least important aspect of our trip. I do like to stay at places with pools, too. I do not like driving to DLR every morning because it's not necessary with so many options so close, and walking to and from the parks is a perk WDW can't offer.
My advice to WDW vets visiting DLR is always to put aside your WDW expectations and experiences. This will be a new and different trip! DLR is still Disney, but it's definitely not the same vacation experience. Enjoy the uniqueness!!
To answer your question, I've never stayed at the Carousel. I would, however, be far more inclined to believe the hotel reviews here than on a review site as those have been proven to be biased many times. So, search for it here and see what people have said.