It seems, looking at the questions, answers, and Hubs on HubPages, that grammar, spelling, and writing style count for little. Lots of crap Hubs with lots of backlinks and pageviews from within HubPages and via search engines will result in good author scores.
Ditto for the Internet as a whole. The equivalent of author score on the Internet as a whole is site income.
While a HubPage author score of 90+ is good for ego-boo, as long as it is above the cutoff score to keep an author's links from being tagged "nofollow", he's OK.
I think -- but verify this -- that score is 75.