This is a Popcorn Drift that seems to be infected with botrytis. I'm happy to take care of it myself, but wondering whether a rose affected by botrytis in a garden center setting should be treated or tossed entirely? I'm mainly concerned that it will infect surrounding plants. Is there actually any solution to botrytis, or is the future of this plant dependant on expert cultural practices (which most customers won't be interested in learning...?)

It's not like a permanent viral infection, like, say, RMV.

It's a fungus -- like powdery mildew or rust -- and when the weather turns warm/dry, it goes away. When my coastal climate was more or less permanently cool and foggy, we avoided roses which were troubled by it.

I don't worry much about roses with fungal diseases at the nurseries. They don't have ideal growing conditions. The roses are pretty well packed together in a warm, humid greenhouse setting where fungal diseases thrive and spread easily. Once you get them home in the garden and can care for them properly they should clear up. I'm more interested in the strength and structure of the plant than the condition of the leaves. And I've been known to bring home the half dead, half off ones a time or two just to see if I can save them, lol!