Good question. A older thread but interesting.
Few times I've said I have a store and such and they would lead me to other items. So many times though it kills the chance of any profit. They instantly become an expert on everything and all of their prices are a steal in their mind all of a sudden. Even when I tell them I've sold 10 of those gaming consoles and for x and they want y. A few times I've offered very close to retail just to obtain a unique item but they feel they were still being taken.
So basically now we quickly get a feel for the person. Ask about their situation first. Need to sell from a death in the family, moving, lost job...Boom here's my card. I can buy it all. Cleaning out the garage and they don't appear to need money..."I buy and sell and collect a few things" toss out a joking "Don't call that hoarders show on me" to quickly divert attention from the "I sell". Throw out a "Billy collects these" to my wife here and there. It's a fun game.
Although my town is large (800k) I've ran into quite a few customers. Most recognize me first and that's why I never just lie and say I collect.
All in all we've done better by telling the truth and networking. But it's those rare situations that bug me where they feel I'm the bad guy. I'm not out to rip anyone off. Unlike me, they don't have to pay local sales tax, pay Uncle Sam, insurance, lease, employee wages, utilities, and so on.
One lady was yelling at me at a yard sale. She had gaming consoles. Told me to make an offer. I told her I had a store and what I could pay and get for the one I was interested in. I told her the retail prices on all the others as a friendly gesture. We do that a lot. She said she wants the price I can get. She now loudly says to her friend, "Hear this? He's trying to make money off me". Uhh lady it's capitalism. I make money because I've done my homework. You had no idea what you had. You own your belongings from work (I assume). I'm working. Wish I said all of that to her. I just walked off. Come to find out a week later she posts on my facebook about a rocking chair we were selling that my wife bought from her yard sale the day before I went. She said " Oh I had one just like that". lol