Fluff bunnies, fluffies, whatever you want to call them, it's a topic I've seen going around a lot recently (and not just with today's PBP "F" topics). Some people really take issue with this term, while others don't have a problem with it. From what I've seen, One of the big problems is that there is no real single definition for what a fluff bunny is.
Some people use this term to describe those new to paganism, those who don't know much - but are trying to learn, or those who make common beginner mistakes. To me, it doesn't really make much sense to insult those types, to look down on them. We were all beginners once, after all. We all had to seek out the information, and if there's anyone out there who never made a silly beginner's mistake? Well, I would seriously doubt that claim...
Then there are those who use the term to describe anyone who practices a path that focuses more on the lighter stuff in life, the 'fluff.' Well, it's not my cup of tea, but if it's legitimately fulfilling to them, then I don't really think it's any of my business. As long as they're giving me that same respect, then to me there's no problem there. Sure, some of them don't respect anything but the 'all light all the time' paths - but, truthfully, there are plenty who look down on the whole 'love and light' thing too. It goes both ways. (And, of course, fluffy is sometimes also applied to the other end of the spectrum, the whole doom and gloom bunch. Same thing with them.)
I think though, in most cases it's used to describe those who lead a shallow spiritual life for show, for the attention. Or for those who want to remain willfully ignorant. These are not the people who are honestly looking for information, these are not the people who pick up incorrect information along the way, but are willing to adjust when presented with correct information. These are the people who ignore the facts that don't fit in with their views. The people who claim Wicca is an ancient religion from the stone age, unbroken in practice - or the people who claim that millions of people were killed during 'The Burning Times' - and absolutely refuse to acknowledge that their facts are easily proven wrong.
Now, a question often comes up with that last group - why does it matter if someone is willfully ignorant? After all, they're only hurting themselves, and no one else, right? Well, no, they actually are hurting people. Purposely spreading misinformation hurts the people looking for the actual facts. It muddies the waters for everyone. Especially when you have some 'popular' authors, authors with books which are easily accessible to many people, doing the same thing. It's the sort of thing we should not let slide by, because it hurts our newcomers (and at times even those who've been around for a while), and it reflects poorly on paganism as a whole.
Truthfully, it's because of all these variants that I don't really like the term fluff bunny, and it's why I don't use it myself. It's not that I have an issue actually addressing problematic behaviors and the like, but if I say fluffy and mean X, but someone else thinks I mean Y, and yet another thinks I mean Z...? Well, I guess I just find it more helpful to be specific with these kinds of issues.