Welcome to OpenStreetMap :-)

Yes, they can:

https://wiki.openstreetmap.org/wiki/Tag:waste%3Ddog_excrement

(just about everything can be added: if you aren't sure how, there's probably a solution already; and if not, a solution can be developed. 

Setting a note is a good first step, or you can try the many other sources of peer advice:
https://wiki.openstreetmap.org/wiki/Get_help )