I mean there are some objective standards that can be applied.So then I suppose it all boils down to whether or not a person thinks a particular dojo is a good dojo to train at and the standards for whether or not a dojo is a good dojo to train at will of course vary from person to person. A politer way of saying it would be to say that a particular dojo doesn't meet your standards as a dojo that you would train at, the term mcdojo can be offensive.
Is the dojo/gym competing and having regular success fighting? Preferably not only point fighting, and definitely a red flag if all their wins are from in house competitions only.
Is the dojo doing real resistance training?