Yeah. Been in that situation too. I believe they can address it by allowing us to enter the raid lobby without losing our raid pass. That way, we can be sure there are others waiting as well. Not all "hidden" trainers are spoofers though. Some are just inside their car, inside a nearby establishment, etc. Some will probably say, "Don't commit if you don't see any one playing." Well... You still can't be certain even if that gym raid is inside a mall or a park. Not all people play.
Right before work, Tyranitar raid pops up. I tell myself i can be late to work 10mins or so. Sit at the gym for 5 mins.....NOT A SINGLE PERSON. Not even anyone relatively close to showing up. First time i have ever seen a Tyranitar Raid for my self. I guess my question is, has anyone else had this bad of luck? I am sure if i sat there for 20-25 more mins some people would show up, but not trying to lose my job by being 40mins late.
Answers
2 raids I took part into had 2 spoofers who joined!
First was a level 2 Muk, and I recognized the name of a Famous spoofer of my city.
Second it was a level 4 Snorlax, we were 5 people at the place (met so many people with raids, and now we created a city group...that's awesome about raids!) + 2 other trainers joined but weren't there physically Lol
Try starting a Facebook group of known Pogo players in your area and create a group chat out of it. That's what we do here (city of 50k). We usually max out the lobbys and have to split up into our representive teams so we can get extra premiere balls. Of course if you live in a smaller city this might be as useful but could still help out a lot.