I tend to keep an eye out for threads without many (or any) replies but if I've not got anything to say then I often won't post in them. Once in a while I'll bump a thread if its a day or two old and I'm hoping someone else'll have an answer when they see it, but generally I just trust someone with an answer will find the thread themselves.
I did see this and another post of yours yesterday that at the time had no replies. I didn't comment in this one as I wasn't sure how to phrase what I had to say. I didn't comment in the other one as it started by mentioning a thread I didn't remember and I didn't want to hunt down a previous thread to try and make sense of the new one. Without context I doubted I'd understand properly so I left the thread and hoped someone who did remember the previous thread would see it.
Its like Souffle said, none of us can read/comment on everything. I read a lot more threads than I comment in, I could comment "Oh thats cute" 40 times a day but I'd get bored and it'd look like spam... Or I could comment "I'm not sure, maybe someone else will know for sure" 6+ times a day every single day but chances are I'd cause more irritation than anything else and would end up with a mod asking me to stop copy/pasting my answers lol
Its much better for me to spend time on answers on threads where I think I can help and to leave the threads where I can't for people who can
Yeah I look for threads by my friends and some forum members more than I look for ones by others but if I do/don't reply isn't anything personal. I read almost every thread I see by Souffle - it doesn't mean I comment in them all and I doubt Souffle minds that I don't always comment just to compliment Tiber again (for example).
I also looked at your threads last night (so before Souffle saw this thread and shortly after you posted it) and the vast majority of your threads had replies. The two I'd chosen to leave didn't but I think all the rest might've, I definetly don't remember any others that didn't. It really isn't anything personal if people don't reply, its just how forums go sometimes I'm afraid. (Infact sometimes loads of replies is a worse thing, I've seen a few people end up seeming to think people're ganging up on them over pet care. Its not whats been intended but too much of the same advice can definetly look bad from some perspectives at times.)