Fraud attempts? Usually we get at least 1 signup every day or two (so 15-20 per month). How many get through? Very few (if any). We run fraud screening with MaxMind and voice call each signup (even in foreign countries). We do not have any automated setup, everything is done by hand by billing supervisors so that each account is screened correctly.
People failing to cancel their hosting or domain names with us, and then issuing a chargeback at the credit card company - that's a different story (we consider that fraud). We provide a service, and a person skips out on the bill, or issues chargebacks for the previous month or two. Pretty underhanded given that they receive invoices at least 14 days PRIOR to the start of the new term.
Any user who does that with us is blacklisted on our servers from any future signups. Depending on the location of the client, and the amount, we also file legal charges, along with normal credit card disputes etc.