Technically, I don't detail for a living, but I can draw comparison to my own industry.
There was a time when I said yes to everyone, even the "walk ups" who see me mowing, usually from the house across the street, and ask me if I can do theirs next. These people always want the job done immediately, want it for the less than I have asked for, then expect me to do a bunch of "while you're here's" for the same price. This situation never, ever, leads to both parties getting what they want. I end up taking on a job I didn't have time in my schedule to do, for less money and often the job takes waaay too long because of neglect that I don't make a cent from it. The customer then either gets the deal of a century or ends up disgruntled because I can't/didn't make silk purse out of a sows ear.
In some cases, the above would lead to a regular, scheduled job. And again, it leads to trouble. On one, the owners of this property lived out of town, it then became a situation where I was being called on Sunday evenings over trivial issues that really weren't my responsibility.
On another, the lady bartered me down from what was already a low price, would call me to schedule a cut once a month with a day's notice. What should have been a 15-minute job would end up being a 45-minute job due to length she would let the grass grow, meaning I was basically paying her to mow her lawns.
After mentioning my maintenance business to one of my nursery customers, somehow my number was exchanged with the idea I could "potentially" do some work for her in the future, but no promises were made. Last year, while the bloody town was flooded, she started sending me messages and phone calls demanding that I come around and clean her pond pump filter because she "doesn't like getting her hands wet and dirty", all while large portions of the town were under water, and I was trying to manage the nursery while my three managers were dealing with flooded homes. She then got p.ssed off with me because I wouldn't drop everything for her or make an afterhours visit to fit it in. I then got lip because no one in town would help her. All over a small piece of foam in her stupid duck pond.
My policy for a long time now has been NO WALK UPS, they are never worth the bother, nor can I deliver the result I want my name next to. I simply just tell them that I'm fully booked, not taking on new customers or that I simply don't have the time.