Here's a few things to consider. Thanks to my son's moron girlfriend, who feels stopping for red lights is something other people have to do but not her, I just had to list his now wrecked Mitsubishi Lancer for sale on craigslist. I never post my phone number in craigslist ads because I don't want to be screening calls, so I only post my email address. Within two days I had 14 emails from potential buyers.
Of the emails I received, some were from obviously interested buyers. Some provided me their phone number, asked relevant questions about the car, and stated they had cash in hand or made me an offer. Others were limited to "Call me at 904-***-***" or "I want to get it." I know there are a lot of scammers, so if someone emails me and doesn't provide a phone number or doesn't sound like an interested buyer, they never hear back from me.
But even for the guys who do seem legit, I contact people in the order their emails come in. In this case, the second guy I contacted ended up buying the car, and the rest of the folks never heard back from me. That's because I don't want to email them and say "Thanks for contacting me but the car is sold" if there's any chance the deal could fall through. Fortunately this guy came out and paid a deposit, then came back two days later and paid the balance, but I have had guys ask me to wait for up to a month to complete a deal, so I can see where a seller of an expensive car might not contact you back if they're waiting on someone who contacted them earlier to complete the sale and they don't.