Bad software is bad whether it's open or not. But historically, closed software has more lock-in. If a particular open lib or component is bad, it can often be fixed by somebody who didn't create it. Or, for those who don't want to touch the scary hairball, it can often be replaced by a completely new hairball written from scratch by a completely different party. Even if there's nothing broken with the original, open software is friendlier to alternatives. It might take a bit of work, but you can replace one open part with another just because it's shinier or smaller or faster or not Oracle or whatever.

I don't trust all open source software, but I trust it by default more than I trust closed software. And I know that if something really bad gets exposed the odds of a solid fix are better in open source. I get to see the warts of OSS. There's public criticism over small details on a lot of important projects. That doesn't happen for closed stuff. Sure, a vendor may have four of the brightest devs in that field and they might hash it all out behind closed doors. The open alternative usually has another four of the top 12 minds in that field along with four pretty competent others and they have a better process for hashing it out.

Then there's that other guy who's not in the top 12 who goes it alone and comes up with something spectacular. So three of the four from the other open project jump on board because they can. And since this new project tries very hard to be backwards compatible, it just snaps in as an overnight replacement. That's part of the awesomeness of OSS.