mohawk, I would wonder that too but I would wonder the same about a $300 filter as well. Is it really about the chaep glass? Is it more about the reflections or possible ghosting caused by those?
Don't think I've ever seen a pic posted using a cheap filter versus a good filter where at 100% one could actually see a difference.
I've seen a lot more CRAPPY shots posted where shooting threw the bottom of a coke bottle would make absolutely no difference.
So are these really good filters actually better, or is it all placebo?!
I'd sure like to see it, NOT just hear about it.
Is ANY filter better than shooting without a filter?! I'm not talking about specialty filters like CPL's and ND's.
For me the proof is ALWAYS in the pudding. Until then, it's just talk!!
Either way I haven't seen it!!!
mohawk, this isn't directed at you, it's for anybody that can come up with a sample shot, that's they took, NOT from a filter company or ad!
SS

For relevance, I shoot Nikon bodies and lenses (listed below). Been using BBF for several months after seeing posts here and viewing videos by Tony Northrup and Steve Perry. Most shots sharp but every so often I would see one that was out of focus (sometimes a little sometimes more). I would just chalk it up to camera shake, operator error and move on. The next shot usually sharp.
I have Steve Perry's e-book "Secrets to Stunning Wildlife Photography." In his discussion of BBF, which was not mentioned in the video, he cautions that once BBF is used to lock focus (push then release) do not move the focus ring on the lens as that will engage manual focus and change the locked setting. I find in holding the camera it is easy to move the focus ring inadvertently. So, I use a piece of gaffer tape to hold the focus ring in place. If I need to manual focus in Live View just pull the tape off then reapply when going back to AF.
I also find a piece of gaffer tape across the VR and focus buttons on the lens prevents accidentally bumping those off-setting which I used to do often enough to be a problem.
Hope this is useful.

Often people make observations, and comment on them, without necessarily considering all the possible scenarios. It doesn't mean they have an agenda and it doesn't make them trolls. Could he be a troll? Yes, that's possible, but then so could you since your somewhat accusatory post could be construed by some to be an attempt to start a controversy. I don't believe that, and I don't believe the OP had an agenda at this point. I like to give people the benefit of the doubt when there is no evidence to the contrary.