Even if something is relative, you can compare it to what other people believe. If most people who know person X think X has "good taste" (that is, that their

Even if something is relative, you can compare it to what other people believe. If most people who know person X think X has "good taste" (that is, that their tastes more or less agree, or at least that they aspire to having similar taste like how more people admire those who like classical music than listen to it themselves) then it is reasonable to say that person X has "good taste".