Visa has defined several types of merchants as being higher risk.  Such merchants usually cannot qualify for the best interchange rates.

High risk merchants include the following MCC codes:

• Direct Marketing – Travel Related Arrangements Services (5962)
• Direct Marketing- Outbound Telemarketing Merchant (5966)
• Direct Marketing – Inbound Teleservices Merchant (5967)

Credit card processors also have their own criteria for what types of businesses are high risk.  The processors opinion of the business risk can impact whether 1. they are willing to do business with the merchant at all 2. the rates / markup over interchange that they offer the merchant 3. any holdbacks or other risk-mitigation costs that they will assess.