I wanted to start music forums, a long time ago, but at first, they were hindered because I couldn't stop spambots. Also, I never ran into or thought about forum promotion forums. Anyway, my first attempt was phpBB but too many spambots, so I moved to SMF which had less, but I think eventually, of course, SMF probably also got spammed out.
Anyway, the downfall was inexperience with spambots.
So your abandoned project should be spam free bot. Add some level of extra protection. So what made you work then leave it then work and leave it. Considering getting good members to keep it alive and active.
I'd say the biggest thing was simply not having people posting on it, cause as I said, I never thought of forum promotion sites. However, though, since SEO was easy at the time, I believe I got a lot of traffic to it, ironically.
No, just switched to XenForo, but so many of these forums are just lying around, but I am getting @The Prince to help with some. I think a big problem, though, was, in the past, I had this guy claiming to be a partner and he didn't do one red cent worth of work, even though, I promised nearly all the profit to him. Anyway, it's mostly because I wasn't around the right crowd.
I don't think I've encountered really bad software - except maybe that on MyBB sometimes you can make paragraphs but they don't show up as that. Instead, you have to edit it again to get it right. However, that might be due to lack of updates on the part of the owner.
I never abandoned any forum I ran. I have closed a couple though, which isn’t the same thing. Members were notified that I was going to pull the plug soon. I think abandoning is worse because members are left confused and wondering what’s going on. It’s better to be direct and let everyone know exactly what your intentions are.