Well I just recently joined, but I've published 4 hubs and my average score is a 69. However, my scores are still continuing to move up each day, so it may be different with a couple of hours from now as my scores have already changed once or twice within the last 12 hours. I feel that I would delete a low scoring hub only if I couldn't get the score up and I didn't really care much for the message being presented. For example, if I put up a book review and it keeps a low score I may get rid of it. However, if I'm posting a hub about a topic I find important and it happens to get a lower score, I'll probably keep it anyways, because I thought it was an important message to get out there in the first place.