These types of apps are very useful(although the game NEEDS to add one for authenticity!), But the screening process should be Very strict either way! So that updates like your newest one that flags markers as fake/wrong wouldn't even be necessary. And it's Always better to get it right the first time, rather than finding too many fakes, which in-turn would make people dislike/hate your app. Don't get me wrong that type of update will always come in handy, but it's Always better to get it right the first time!

If there's not a way to have the Pokémon Go app record the information somehow, for verification processes, then these types of apps will never be very "reliable"(Sadly the world is FULL of trolls!). And there's Nothing worse than walking a couple miles(over and over sometimes) to get that rare spawn and its not real!

That's why I prefer apps that focus on Nest spawns, rather than one random person catching one random Pokémon somewhere around some spot! Grants super rare Pokémon will probably never have a set spawn either way so collecting data where they have before could be a complete waste of time. Just because a Pokémon will spawn there once, doesn't mean it Ever will again. I've had a couple different rare spawn on my block that never spawned here since. Magmar and Electrobuzz only once each in nearly 3 weeks of searching, and always leaving the app on while at home.

I'm just saying Nest spawns are where it's at!! Guaranteeing exactly which Pokémon you'll be getting on a very regular basis(Every 15/30 mins, for the 5 spawns I know of in my town!). On top of that you still get the randomness of other rare spawns showing up there too. It hasn't been long enough(about 2 weeks of studying them) for me to verify if those nests have any effect on other rare spawns or not, but I'm working on it :)!