Have you noticed that posts with characters in nazi uniforms also get downvotes? The thing is, not everyone likes their characters being assigned words and beliefs that they never even thought about.
A quick look at original lgbt_pride proves this is not the case. Just look at post #7711638 and post #6439537. Both perfectly fine original posts, but they got downvoted because they display pride flags.
At the moment their rating, despite downvotes, is positive.
Now you shifted the goal post from "downvotes" to "positive score". People downvote LGBT posts because they don't like LGBT. It's that simple. Your P.S. is very ironic because you tried to discern a pattern that doesn't exist.
Not really. Out of all the original nazi posts on the current first page only three of them currently have any downvotes at all, whereas every single post under original lgbt_pride has at least one downvote (and only one of them has only 1 downvote).