As it was recently discovered, Pokemon Go users have found (or, at least, they think they have) that OSM data affects Pokemon "nests" location. Some of them immediately started adding fake map features. Here are several examples: Washington, Indiana, United States, this user https://www.openstreetmap.org/user/forever2darkness/ , fake residential areas and footways. (Reported to DWG)
Charlotte, North Carolina, Unites States, this user https://www.openstreetmap.org/user/Fishboy35 , fake parks, with the obvious names like "not an actual park" (Reported to DWG) And guess what? He got a welcome message for adding these fake features https://www.openstreetmap.org/changeset/45538011
Hi and welcome to OpenStreetMap! You've been adding some great detail to the map since you've joined. We count on local knowledge to make the map a better place! That said, please make sure you're only mapping real objects. Things you add go into the live database, which is depended upon by businesses, governments, and even humanitarian organizations. If you have any further questions about mapping, don't hesitate to give me a shout! Best, Ethan aka FTA
It was sent automatically by https://www.openstreetmap.org/user/FTA . How nice of him.
Assuming that they are interested in adding fake lines and areas, not nodes, this Overpass query could be used to load objects, last touched by a specific user, to look into one's activity. http://overpass-turbo.eu/s/lzL Keep in mind, that not all changed objects are added by such users, some of them are only edited. Do not delete all of them without examining them.
One important thing: I am not saying here that all mappers, who are Pokemon Go players, are adding fake objects. I am also not saying that they can not add real ones. I'm only saying that to prevent adding fake objects in the future, it is important to delete these as soon as possible after they were added. And only after that anyone could try educating these guys about OSM.
Update: a certain DWG member I've contacted preferred to preach about being polite with new users and teaching them to be nice instead of helping to remove that trash. It seems very "cooperative".
Update #2: It looks like at least some of obviously fake objects were removed by DWG reverting robot.