What's Sincere and What's Scam?

I've gotten a few emails this week in regard to DYING EMBERS (which is still free through the end of today).  Most of them have been obvious - people trying to get me to pay them to market my book.  One of them, on the other hand, was someone wanting to use my book in their book club.  I've been on the fence with that one re: sincere or scam.

I mean, he seemed sincere enough.  He talked about my book like he'd actually read it.  He said intelligent things.  Unfortunately, so did several of the scammers.  (In all fairness, the marketers may not have been scammers, but for brevity, and because it's so hard to tell the difference, I'll call them that.)

It's a minefield out there.  How does one tell the difference between someone who is sincerely interested in a book and someone who's trying to part you from your well-earned and miniscule profits?  (I'm averaging about $18 a month here.)  

The idea that I may be ignoring someone who is sincerely interested in my work wrecks me.  I lay awake at night thinking about it.  I'd be willing to interact with them.  (I almost said like or love, but the idea of interacting with strangers makes me nauseous.  Hell, most days, I don't want to interact with anyone but Hubs, but that's on me.  The older I get, the more hermit-like I become.)

On the other hand, interacting with scammers - even just a little - is bad.  You even bother to tell them 'no thanks' and suddenly you're inundated with crap.  Who needs that?

So, I sit here, torn between knowing I need to interact with fans/readers and wanting to stay as far away from scammers as possible.  It's a slippery slope to hell either way.

What do you think?

(For the record, I deleted the 'book club' email, but didn't send it to spam like I do with all the others.  If he emails again, I'll think about this some more.)