Hi Chris :-) Welcome to the confusing world of entrepreneurs.
Reading your above story was interesting. It got me thinking about a classic direction many people take when starting a business. It`s the question of when to charge money and when to offer "promotional" work.
It reminds me of a major argument I had, back when I was in the music business. I was the leader of a band and a friend of mine was a pro guitarist who`d been around for quite awhile. He didn`t want to run a band, but wanted to play what I was playing.
As we were starting, I suggested that we might do a few talent nights, sort of like open mic, where we`d go in and play 1 night in a club for the promotion. He totally and adamantly nixed the idea. We had, as they say, a "frank exchange of views." Quite loudly, it turned out.
His argument was that NO business is a business if it hands out the product for free. My argument was that a business couldn`t become a business unless it ALSO had a market.
Eventually, he convinced me with massive proofs, background, examples, and demonstrations called up from my own history.
What you could have done with your detailing operation would have been to charge your expected rate for the detailing, but also offered additional services or options as a "promotion."
For example, you would charge $1-million to clean and wax the car, do the windows and vacuum the interior. But for the promotional startup offer, you could have offered the interior vacuum for free, or perhaps cut 50% from the wax job. Things like that.
When you offer the entire product line for free, nobody takes you seriously. As you found out.
The bottom line is that if you`re convinced that you have a real product for a real market, then don`t give it away for free. The proof of ANY business and idea is whether or not it works! And in a business, "works" means that it generates revenues. If it doesn`t then there`s something wrong either with the idea itself, or the implementation.