Could you be more specific as to which lots you're referring to? Names or pictures?
When I go back and play tonight, I can be more specific, but in my case, many, many community lots are "no visitors allowed." (Ok, I found a list of lots here so can give more specific names). Some I suspect are for EPs I don't have, like there is a movie studio lot like this (UC films and Features). There is also a lot that near the city hall that is called Center Park Shops which is no visitors allowed. These are just a couple of examples, and I suspect many of these are clubs (see below).
I found the post early on in this thread which at least tells me what some of them are (in my game some are not named at all):
http://www.carls-sims-3-guide.com/forum/index.php?topic=8363.0 so I have a list to work off, but I'm not sure why so many are no visitors allowed? I don't have all those clubs that are listed (say, for example, a club called "Jungle Love" that is a disco club, or The Grunge, and there is a no visitors allowed exclusive club in the Asian influenced area that I suspect ) and so I'm thinking that the buildings that were made for EPs I don't have are now just showing up as unnamed community lots and have reverted to "no visitors allowed."
If that's the case, I can probably either delete them or change them to visitors allowed and use them for something else. I wanted to ask, though, in case people think that's a bad idea and might make something go wonky in the game.