This game was poorly thought out and it's only a matter of time before it makes the news for someone getting hurt.
If you sign in with your Google Account, you are giving Niantic FULL ACCESS to your account. That means they have access to everything in your gmail account, emails, contacts, IP addresses, etc. You can remove this access after signing in by logging into your google account on a desktop, but one you sign in with it again in the game, you give the access back. I suggest making a new dummy Gmail account and using that.
Well you can fill out a form on their site and request to have your previous account (tied to the specific email) deleted. But they say it takes several weeks.
I haven't tested this theory personally (still need to catch a few more Eevees) so take this information in whatever way you want.
https://65.media.tumblr.com/7cf0d6f3e4d3a2ca41ba3e7320b71c68/tumblr_oa2fc2D6jB1vzjnvio1_540.jpg
I dont know if its because i dont have a great connection or what, but im getting constant errors trying to catch things, or even power up pokemon. Aside from the server issues.