How to differentiate bad from good orchestras?

Near my town, in the city. There is an orchestra, that's probably less professional than you'd see in here. Even tough the "bandmaster" or whatever the translation is, keeps telling us that we are pretty good in comparisons to other ones in our country.

Is it true? What makes GOOD and what makes BAD orchestras?
I can provide a link for the youtube of it, but its outdated.