Tutor Vista tried to charge my credit card 10 times after my subscription ran out and I had already canceled. Lucky for me my credit card company contacted me and told me who was trying to do this.
My credit card company told me they tried ten different times, starting at 100.00, all they way down to two dollars when attempting to charge my card. I of course told my credit card company not to allow those transactions, in which they handled the rest of the attempts. Tutor vista was very helpful when I needed help in my math class.
However, I don't think it was worth the hassle of babysitting my subscription to ensure I wasn't charged again and again. I don't think they are honest at all, and you really have to watch your credit card statements.