What would you do if a dog came to you with fleas?

I would make it a written policy that a dog with fleas will get charged for the bath, and clean up Costs. Think of the time involved not just bathing but cleaning your house, bedding, flea bombs-…so not just for the supplies, your time is valuable.

I would recommend you tell the owner that you found fleas and you bathed their dog to remedy. Whether you submit request for service modification, adding a bath, is a judgement call you’d have to make on a case by case basis. I’d consider: Since they were there two days, could they have picked up those fleas when outside, during walks, after arrival ?

I know entirely too well what you’re talking about washing every soft surface. in your home.
Even though the dogs who stay at my home are on flea prevention, there have been rare instances where the owner’s chosen preventative did not protect them against fleas. Around that time, vets confirmed they were being inundated with flea outbreaks from their clients who were using some prevention. In my experiences, the dogs arrived clean but when I noticed the fleas, I used a flea comb with dog shampoo that was on hand. This happened with dogs whose owners I had built solid long term relationship with and didn’t charge them for the bath.