So I never thought there was anything interesting in terms of Pokemon Go in the area where I live. I live on a main road leading into a city, so I'm on the outer edge of the outskirts. The only life near me is a collection of five pokestops and two gyms in a mental institute a little down the road. I never go there because A. it's creepy, B. both gyms are level 10 and dominated by Team Mystic cheaters (I posted evidence of that earlier), and C. I only ever see common Pokemon on my nearby list at those stops, so it doesn't feel worth it to me.
Today I had to get a bus to the city. My closest bus stop is just past the entrance to the mental institute, where one of the pokestops is. When I got on the bus, I noticed there was a Sandshrew at the stop by the entrace, which is funny because I've seen a Sandshrew at that stop a few days ago, but I thought it was one of those rare once off spawns. On my way back from the city, there were
two Sandshrew there. So, apparently that Pokestop I've been ignoring is a Sandshrew spawner! Which is great because I only needed two more to get my first Sandslash, so that's one dex entry I got to knock off the list today.
Also, while I was waiting at the bus stop, I noticed there was a Charmander in the mental institute. Again, I thought it was a once off thing. Again, on my way back, I saw another Charmander. (These weren't affiliated with pokestops, they were "sightings", so I never saw them from my house. When I'm at my house I pick up on "Nearby" Pokemon that are actually inaccessible from where I live, so I never get to see Sightings from there.

So TIL my local mental institute is a low key nest. I spent around an hour there grinding enough Charmander candies to FINALLY evolve my buddy into a Charizard, so I got that done today too. :')
I'm choosing not to add it to the Global Nest Atlas because a lot of elderly demented people live there and they appreciate minimal traffic and noise from us "youngsters". P:
I've been walking a Charmander for months haha... Now I've buddied up with Clefairy. If I walk 4k I'll be able to get my first Clefable!
So I guess what you can learn from this is never just go by what you see on the Nearby list. Always do a little exploring.