I always check out their member area. I need to see what i am offering my visitors. (hosting, amounts/quality of content, updates, customer service...)
I always check the Billing pages, makes sure they don't have crazy Cross sales, i don't want my Surfer to get charges $110 for a membership.
Then of course, webmaster area: tools, payments (methods, delays, reputation etc...)
The one in my sig has passed all those
