Mom in nursing home and all she does is complain. Any advice?

After a recent hospital stay, my mom had to go to a nursing home for physical therapy. Afterward she would be returning to an assisted living facility which she is eager to do. From the first day, all she has done is complain. The food is too tough/tasteless/spicy/hot/cold. The nurses or aides don't come fast enough and when they do come around, finally, they are rude/act smart, leave too quickly (who wouldn't). You get the picture. Due to her low blood pressure, therapy hasn't progressed as quickly as she'd like. Either I or my husband visits each day even though she's about 30 minutes away. My dad is in a different NH only about 5 minutes and has an awesome
attitude, very upbeat. You can probably see why he didn't want to be in the same facility as her. My problem-I hate going to see her and when I do, we argue because I point out positives in her NH. I purposely try to be a Pollyanna about everything she hates. How can I be around her without wanting to stick a sock in her mouth? This could turn into a longer stay if she doesn't shape up and put a little more effort into her therapy.