And most of those are the ones actively discrediting the 'good' ones because they've been paid off by the fossil fuel industry.
You know, that statement right there shows why the public has no problem believing that scientists can be just as corrupt as politicians. It's not the "bad ones" who have created the problem, it is the "good ones" who dismiss anything any scientist who is "paid off by the fossil fuel industry" says just because of who they work for.
Once you have one part of a group pointing fingers at the others saying "they're corrupt", it is not very hard at all to think that all of them could be. I mean, if who pays you determines what your results are, then why wouldn't someone being paid on a grant to study one aspect of climate change be likely to find just what he's being paid to find? Even if it is nothing more than unidentified confirmation bias, if who pays you can point you to your results, then that applies no matter who pays you.
Why would none of the academics publish biased results?
1. There's no profit. Of course there is. Grants go to people studying new and/or important things. If you say "there's nothing to see here" your grant doesn't get renewed. You have to go find something else to work on so you'll get paid. Unlike people with real jobs, academics don't get paid with their employer's money, they get paid from grant money.
2. Someone would snitch. Of course. And then that someone would wind up without HIS grant because a) nobody likes a snitch, and b) "there's nothing to see here" applies. Unlike someone with a real job, academic grants go through "peer review" and if your peers decide that your work is banal and obvious, you don't get your grant.
Of course, the bias may not be deliberate, it may just influence what "outliers" get thrown out.
If you don't think there are egos involved in academic science, you've never worked in academia. If you don't think there is back scratching going on all the time, ditto. There is a limited amount of money being pulled in a large number of directions. Anyone who says "there's nothing to see here" jeopardizes everyone working in that field, and those humans called "scientists" can still do what humans tend to do when something jeopardizes their income.
Personally, I just wish those "good ones" would stop accusing their colleagues of being bought off, because it besmirches the entire process of science. If you can't counter their science with your own, then maybe you need to look at your own science first. This "you've been bought off so you are wrong" argument throws mud on the recipient, but a lot of it splashes back on the thrower.
Seriously though, what evidence do you have that 'a good chunk' are corrupt?
The same evidence the "good one" have regarding the "bad ones".