Like anything else, some of those standards can change with time. Trends come and go quickly. Some things, like a particular fur pattern, or some little superfluous trait might get popular then become unfashionable just a few lives later. In my last life, I had these little ear tufts that everyone was going nuts for. Then out of nowhere, whoever makes fashion trends decided that the things looked silly. A lot of people still have the trait now. Mostly folks that jumped on the trend just before it was ending and are stuck with them for however many lives it takes them to shed the trait.
That’s just fashion, though. Deeper standards of physical beauty take longer to change. In general symmetry is a big one, although that doesn’t necessarily apply to fur patterns. Looking healthy and alert are important. Remember, when you’re sired by someone, you take on half their genes in your next life. Physical fitness and a good mind are determined by genes more than anything else. Large irises thinly sloping features are generally seen as very attractive as well.
Physical deformities are pretty unattractive as far as most people are concerned. Mangey looking fur, loose hanging skin, and things like that are If you’re really dirty, or lazy, or sick, then you’re not going to win any beauty contests. A few lives ago I had ears that were much too long, and one would always bend down. I worried a lot that it looked gross, but the person who ended up siring me that life said it looked cute. That was nice, but I have to be honest, I was glad to be rid of it after I had persisted.
I’m not sure how to answer your question about emotional “beauty.” What people are attracted to in that regard is a lot more personal, I think. Lately, I’ve been attracted to younger, more exciting types. Sometimes I feel like I’m kind of in a rut, and someone like that can remind me to try new things.