In my opinion...
A good thread can be identified by a lot of replies and views as well. I know for a fact that many people will lurk and never post, since most things might have been said already. Lack of replies and many views usually means the thread is viewed, but no one has much to comment on. It all depends on the thread's original purpose.
We have to consider what type of thread it is:
Was it made for replies?
Was it made as a database?
Was it made for an opinion poll?
Was it made as reading material?
Was it made as an information area?
Was it made as a "forum game thread"?
All of these types of threads will have different number of replies. A forum game has little to no posting value, but they are fun and usually have a high post count when they are successful. A database can have lots of useful knowledge, but there is usually little point to reply to a database unless someone feels compelled to comment on the information for some reason (which is usually narrowed down to an opinion). Story threads can have a small number of replies but a lot of reads. Opinion poll threads can be seen as successful if many votes are tallied, yet no replies may exist at all. If the original poster is clever and finds a way to encourage people to respond as if their post is important and will matter, it could bring in many posts as well. To avoid being too redundant I'll end my thoughts here. I'm sure everyone gets my point by now anyway. ^ ^;
TL;DR- In the end, it all depends on what the thread was intended for. The "success" of a thread usually depends on the thread's original purpose.