Friends? Or Booty Buddy?

So my last post, and one of the responses has led me to delve into the realm of friends with benefits. This is something on which I have personal experience, and I have developed my own theories and rules on the matter, so I thought I would share.
First, in my world there are only 5 types of relationships. The first is that of an acquaintance. This is someone you know, perhaps you were introduced, but you don't know them that well, and you usually don't know their phone number and would never call them to hang out. The second is that of a friend. Now I hope I need not explain what this one is, as by this point in your life you should have had at least one of these. The 5th relationship is that of a love. These come in many forms such as a spouse, but marriage is of course not a requirement. You don't even have to date this person, simply love them. In between friends and a love fall two other types that are somewhat related. These are the "Friend With Benefit" or FWB, and the Booty Buddy or BB.
Though these two are related in that in both instances you are having sex with the person, there are subtle differences between the two. And in my great life I have developed rules on how to ensure one does not become the other. First lets begin with the BB. A BB is essentially someone you have sex with...and that's it. You know each other and every so often you get together and have sex. If you want to think of it in this way, it's kind of like an acquaintance with benefits. A FWB, however, is someone you hang out with socially, and then every so often you have sex with them. Now this may sound the same, but oh how the difference matters.
Rule #1 in having a BB - never spend the night. Spending the night implies intimacy, and the key to preventing a BB from developing into a FWB or a love is making sure it stays about sex, and only about sex. Thus no spending the night. Also if you are ever bored (but not horny) never should you under any circumstances call up a BB to hang out. They are not your friends. It's best if you think of a BB as a sex object, and not as a person. If you really want to set up lines, never let them tell you their last name, or even make up fake names for each other. And never should you allow them to tell you anything about their lives beyond a few superficial details. All this is key, because the purpose of a BB is sex. Feelings have no place in such a relationship. In my experience these usually work out pretty well if you follow the rules. They usually only end if someone enters a monogamous relationship (at which point you are free to become friends) or if you just get tired of sleeping with that person.
Now FWB is a little more dicey. Because there it's not all about the sex. Ideally they should be your friend first, and then every so often you have sex together. Now the sex should be spontaneous at all times. If you begin planning it then you have entered dating territory. And you should make sure that you don't have sex every time you hang out. Anything over 30% of the time and you are pushing the boundaries. FWB are hard. These don't normally work out so well as BB, because someone always ends up falling for the other one. So you end up with one who just wants sex and friendship, and the other who wants a boyfriend/girlfriend. I generally advise people to stay away from this type of arrangement. Since you are friends you are going to know all about this person, so when you add in sex, it's really like you are dating but are allowed to sleep with other people. So Im not going to advocate that you rapidly eject from one of these if you are in one now, but be sure to think long and hard before you get into one. Perhaps they aren't really that good of a friend, so you should just be BB. Or maybe you should just ask them on a date.
And so there is my take on BBs and FWBs. There are of course weird occurrences where a relationship can straddle some lines, but in my experience those are novel and don't come up too often.