It is not unthinkable at any sales platform. You even see Brandbucket and similar marketplace names drop. Normally they are picked up relatively fast, but with Dan.com, Afternic, Sedo etc this would not always be the case.
I assume you also had situations where you bought a name on auction or regged a name and then found out the name is already listed somewhere. This would be no different.
I get it.
And I've been the seller who let a domain expire before. Marketplace refunded the BIN to the buyer and cancelled my seller account. One difference being, the domain was forwarded to hugedomains (listed for more money) at the time, when a buyer purchased it at a different marketplace, one that required you to have have your domain pointed at their landing page. If that marketplace would have pulled my listing based off their metrics (as it had been pointed away from their marketplace for quite some time) they could have removed my listing months before the buyer purchased an expired listing.
I can't say I recall negotiating a domain that I wasn't in possession in. As usually, I check to ensure ownership before counter offers and what not.
Nonetheless, my frustration, although rooted in an unfulfilled acquisition of a domain I had high hopes for, is also about verification checks. Understandably this is an Industry wide problem due to yearly "leases" and quick overturn, I feel extra verification checks, either for everyone, or for those who have a history of unfulfilled listings within their marketplace, would help the buyer experience.
BrandBucket, I think, is one of the leading larger marketplaces in their ability to deliver domains based on their verifications. I'm sure some slip through the cracks, given BB redirects can be nameserver based just as Dan can be, which can confusingly leave old listings redirected.
If for instance, any time a domain were to lapse an expiration, even if just for one day, a system triggered the delisting, sent automated email, or halted the listing based on registration status, until reverification occurred confirming the domain is still for sale, or whatever the flagged issue was, had been fixed. This, with the help of a daily bulk WHOIS tool to check for expirations, and changes, might be a huge task, and it may make more work for sellers, but overall, I think more checks and balances will lead to an overall better experience for all.
