The thread they're replying to said nothing about liberal anything, although I would understand jumping to that conclusion if they had.

The widespread vocal opposition to Snopes is not simply from Trump calling it fake news, if anything his was a response just like the rest of us, a response to that organization plainly and blatantly lying to their readers repeatedly.

And yet if you ask people for a list of these blatant lies, most of the time they'll be items critical of Trump or of right-wing talking points.

I'm sure there are some people who don't like Snopes for whatever other reasons but it's obvious that much of the modern resentment against the site is driven by a political agenda.

Well sure, but those examples aren't the result of opposing bias. For the past 5 years any mainstream source or aggregator of information has been on a feverish rampage against Trump. Even if you don't like him it's plain as day. So of course a lot of the prominent examples are going to be that, because that's all they've been doing for 5 years.