I couldn't say emacs developers have poor taste but I could say its' not my taste. I don't have to disrespect them. People think in different ways and get used to different things.
e.g. I might decide that some clothes, although well made and possibly even very fashionable, are not my taste. The superiority/inferiority of taste is something that insecure people focus on IMO. A tasteless thing would be something that doesn't seem to show any overall philosophy of design or something which is bombastic - it goes to town on some aspect at the expense of all others - there's a lack of balance. Even then, who cares?
If I wear a bright tomato-coloured suit because I like colour, why should that make me a bad person? It's only when other people have to accept your tastes because they work with you that they're going to moan about them.
There are some domains where the word “taste” can still properly be applied, for example “vi vs emacs” comes down to individual taste. But then, “emacs people have poor taste” is something that only a narcissist would say. (The “narcissism of small differences” is a well-studied phenomenon).
Or perhaps one uses this choice of words because one feels some sympathy for people who say this in other domains, like “This room, filled with IKEA furniture and film memorabilia, was decorated in poor taste”
… either way, the red flag seems to stick.
The reason it's worth mentioning is that the notion seems to be catching on, and I've seen it applied, for example, in hiring decisions, where I think it's quite dangerous and counterproductive. It lends itself to rationalizing hiring only like-minded people, even where there is no objective ground for preferring one candidate to another.