Gay movies are almost always amateur hour.
Eh, not really. There is quite a lot of shlock, but that's the case of almost every genre
It is like saying action movies are almost always amateur hour because this exists:
And ate least 10 of these gets made for every Mad Max: Fury Road or [insert big budget action film you like here]
Or that II world war films are almost always amateur hour because:
(Yes I'm cheating and just using Asylum flicks, but I can't spend all day looking up poorly made shlock)
The issue isn't the ratio of good:bad films but rather that so few companies are willing to front for LGBT fare in the first case. We usually don't get more than one or two high profile LGBT themed films per year.
So that leaves people with more enthusiasm than professionalism to fill the market. And like my quick illustration above points out, it's not like any other genre doesn't have tons and tons of amateur shlock in them as well, you may not just be as well acquainted with them.