Sims invading home (Private Dwelling Lot)

Some of my observations about this matter:

• Invaders are either fans or teens asking someone to prom.
• With fans it has been happening ever since Get Famous. It happens when you're famous and stops if you quit fame. Therefore I don't think other packs are related to the problem.
• They really don't seem to be using front doors, something I realized after reading this thread.
• On my current game, it has happened in different worlds. First in Willow Creek, then in Newcrest. So, it's probably not limited to any certain worlds. Sliding back doors in both houses.
• I've seen people climb in through an escape window from HSY. This happened a lot in my earlier game several months ago, but I can't remember which world I was in. It MAY have been Copperdale, but there's no way I can say it with 100% certainty.
• In my current house I have those escape windows and a fan probably climbed in through one of them. My back door is a sliding door, but it leads to a closed patio. Those windows are in second floor (there's a way to them, of course) and as my family was upstairs celebrating a milestone, all of a sudden there was an extra person cheering. No idea if he was cheering for the milestone or his idol. I just moved in this house, so this is something I have to keep an eye on.
• In a student housing in Britechester, people quite often walked in through the back door (it was a sliding door, in case it really matters), walked through the house and out the front door and then knocked on it. I don't count them as invaders in same sense as fans and teens, but annoying all the same.