See below.
I have a full time job, and I still find time to go locating.
Then this isn't the business for them.
Think about it. You are doing the work anyways. How are they saving you any time? How many times have you secured a location from a locator, and gone out to place the machine, but found that was refused, or closed, or decided not to place it because it was in a one-man auto shop? You just wasted all that time for no returns. Just placing the machine takes time too. If you have a full time job, where do you find the time to do even that little bit of work. If you can do that little bit of work, you can do a little bit more and go find the locations that you actually want.
Your thread is showing exactly how locators do NOT help grow your business. By your counts, you have been testing 6 locators, for a total of 33 days and have gotten a total 11, and you admitted that at least half of those are mediocre at best. That's more than 5 days to get just 1 and iffy location.
Since you are doing a test, why don't you test your own abilities, and see where they fall with regards to these locators. Even taking one day off a month to go do your own locating should net you better results than the typical locator. If you try my idea and offer a commission, (signing bonus, finders fee, whatever you want to call it) to the owner, you could increase your closing rate dramatically.
Giving that money to the locator to find you some good locations does not guarantee that you will get good locations. Giving that money to the location owner of the location that you really really want is much more efficient.