Totally impractical solutions as there is no way to get the exact coordinates of the power spots (does not show on Ingress Map) and those things come and go every 2 days and may not come back before several weeks. Some Power Spot also have very long or inintelligible names, making retyping those in the chat impractical.
Adding a 6th or 7th option to report on the fly “Invalid location” or “Does not exist here” in the in-game Power Spot menu(*) would actually be a much more efficient solution.
(*)The Power Spot menu is currently accessible ingame by very inconveniently (works only half the times) tapping twice on the (?) button when inspecting a Power Spot.