They (the YT-advisors) always hammer on really paying attention to your tags. And it's true, but I've seen certain vids from low sub channels rank up very high while using only 3 simple tags. So it's more then tags alone. The algorithm is kinda messy. I am not even talking about "viral" vids. Ive seen channels, 10-20 views a month on each vid, and then you see one vid popping out with over 150K views with a same style vid. There is now also this kid on Youtube that is hitting allot of views and subs cuz his channel is popping up as recommanded worldwide. Just check "failuresgalore" on YT. It's kinda bizar.