Most of the individual lessons I've had with online tutors were quite good (the one that I described upthread was a rare exception). However, there's a difference between a bad lesson and a bad study plan. A sequence of individually good lessons (the student was engaged and learned something) can yield suboptimal results if the whole study plan isn't well thought out. This happened to me when I tried (and failed) to learn German. I can't really complain about any individual lesson. The problem was that grammar wasn't properly integrated into those lessons. It's not that you have to spend time on grammar during each individual lesson (you certainly don't). But if the student is a beginner, and grammar is absent from one lesson, and then from the next one as well, and then from the next one, and so on until the student gives up, well, that's a bad study plan. Even if each individual lesson was good. After that bad experience, I made sure I made my own study plan for Czech, and the teacher helped me execute it. (Mind you, she might have been able to make a perfectly good study plan for me if I'd asked her to do it. But I didn't, and so we don't know.) I think it worked out well enough: waiting for the results of my C1 Czech exam now... (I hope I passed, but even I failed, I've come a long way. No regrets.)
Now, conversation lessons for advanced students are a different matter. You don't necessarily need much of a plan. The student just needs to be engaged and talk a lot. So for conversation lessons, you don't need the teacher to be any sort of expert. You just need someone you enjoy talking to and is able to offer some corrections. What should
not happen is that the teacher talks 90% of the lesson time and shuts the student up when the student tries to say something.

But I've had literally hundreds of conversation lessons, and the thing I'm describing happened exactly once.