I've never owned a Cougar but......
I believe they are the #1 selling brand for many past years so there are a A LOT of them out there. As such, you are more likely to hear the horror stories that occur with any RV manufacturer. Reading a couple of internet stories of 1 person with a bad unit wouldn't sway me in the slightest.
Buying an RV from any of the mainstream manufacturers and their related price points is a bit of a "roll of the dice." I have to think Keystone (manufacturer of Cougar) were turning out lemon after lemon they wouldn't be selling as many trailers as they are. Fwiw.... I'm currently shopping for a new trailer and some Cougars are pretty high up my list.