While I play everyday it is hard to visit 100 people everyday, so I break it up, I visit 50 a day, but the issue is that I have only about 20 people (maybe ) that visit on a regular basis outside of a holiday event. I try to add those that seem to be active and I don't dictate on what they should tap or not tap.
I think it is just trial and error, during the holiday event I kicked those to the curb that after the first week had not collected any goo, then added others that requested. If they too didn't play or remained stagnant for a while then they were booted too.
You also can't trust your friends list when it says that so-n-so hasn't logged on for 2 months, 3 weeks, 5 days etc because I had someone that visited most days and the friends list said that the person hadn't been on in 3 months! I have since come to the conclusion that the "logged In" means that they haven't come to EA.com and logged onto the website, although I could be wrong.
I also don't cut anyone out just because their SF is small or they don't have a squid port etc, these players can become obsessive with the game and during a holiday even be up in levels before you know it and can end up being one of your best neighbors by the end of the event.
I think a good friend comes to you during the holiday events and try's to click on your stuff and visits regularly, it may not be everyday, but hey.....we all got lives outside of this game right.........right?......ha ha....