Texas has a business tax based on the business assets including business inventory as of January 1st and that has to be filed by April 15th. So if a sportscard business lists their entire inventory on eBay on New Years Day, it in essense publicly displays their inventory value and if the value of the inventory doesn't jive with what's reported on their Rendition Form then that could prove very troublesome in an audit. The idea of listing 3X market value during this time would also not be a prudent move either in my opinion.
It wouldn't surprise in the least to find out that most small businesses in Texas who sell on eBay try to fly under the radar and don't even report anything year-in and year-out regarding their business asset taxes. Some I've heard write-off a substantial part of their home as business, their furniture, computers, motor vehicles as an expense for Federal Taxes, yet never report the same items plus their card inventory on their Rendition form for Texas business asset taxes.
Hypothetically, this could be a problem for a seller in some different ways. For example, lets say a Texas dealer has been running a high dollar baseball card business on eBay and never paid his Texas business asset tax in 7 years and then some disgruntled customer makes disparaging remarks on the internet regarding the seller engaging in unethical business practices. If the seller decides to sue that disgruntled customer, the seller better make sure he has all his business asset tax records paid and in order since it would be rather embarrassing to pay for some lengthy litigation only to come to the realization that you're going to have to admit to the court that you've been a brazen tax cheat.
One other way is by running for public office. It would be rather embarrassing, for major eBay seller to say for example, run for mayor of a town near Dallas and run on a platform of integrity and then be exposed as a tax cheat. Voters tend to frown upon stuff like that.
Here's more if anyone is interested
http://www.hcad.org/pdf/forms/RenGuide.pdf