I am kind of the same way. I express my opinion more often than not. He (WE) just bought another car for him to use that he (WE) picked out. This car belongs in the Fast and Furious movie accept the interior is crap. He showed me several photos of interior kits he was thinking about and chose the fake wood grain sticker stuff. Personally, that reminds me of my grandparents' old station wagon. Well, he didn't like that I told him that. He's the one that sent me all the links here at work looking for my opinion. Why does he always ask for it if he doesn't really want it? He snapped at me for always being "negative". I like to think I'm an upbeat, positive person most of the time. I can't help if there are a few things that just press my buttons and I have negative comments about. I'm sure everyone does.
Lately, I've just been sharing the positives and making faces at the negatives without saying anything haha. I still get my point across, but I don't SAY anything to get accused of complaining or being negative.