Just spray some bleach all around the inside and close the lid for 24 hours. Come out the next day and spray it down with a garden hose. Why would you ever pay someone to do this?
One of the biggest issues with talented people that is relatively common is impostor syndrome, and while it could come off as arrogant, if you are confident in your own ability you will be more likely to succeed and do better as long as you still have determination to complete the job, if imposter syndrome is a bad trait, and being confident in your own ability is a bad trait, that’s a little weird no?
"- best that a customer could find." Saying that is kind of arrogant, it implies you know your service specifically is better than _any_ the customer could find. And that kind of talk is 'too good to be true' talk, so yes, valid red flag.
Charge for the job, not the hour. If you make 120 in an hour, then good on you. Yes, it is OK. Why wouldn't it be. Any company you work for is making more than 120 an hour or they wouldn't be able to pay the staff.