How I handle the “Pick Your Brain” Question now…

A while back, I shared that I was feeling a bit conflicted when I get the “Can I pick your brain?” request.
I didn’t want to be a jerk by saying “no,” but I couldn’t say “Yes” to all of them.
So, here’s what I do right now.
I say,
“Sure, I’d be happy to chat about your marketing issue, but before we do, it would be great if you read my three eBooks CDM, Dandelion Marketing, and Grow Your Fans. Then, since you’ll have the background down, we can specifically talk about your issues.”
What I find is that this weeds out the serious from the non-serious.
I kind of feel like “if you’re prepared to ask for my time (in an area where I make my living) and don’t want to do any prep for it whatsoever, then I don’t feel bad about not giving my time to you.”