Dishwasher repairs: When to say no?

[Loren Whitney]

Hi All, 

How would you handle the following scenario? 

Tenants write you stating that the dishwasher "smells badly" and request that you send someone to fix the dishwasher. What do you say? They have already used Affresh to clean the dishwasher but apparently there is something cause an odor. The dishwasher runs and drains still. 

TIA for your time.