Tax Loopholes For Coin Collectors?

One interesting thing I learned recently regarding collectibles applies mostly to fine art. Apparently if you display an artwork in your home, you're not an "investor", it's for personal use, and thus a loss cannot be deducted. You'd have to have that Monet in storage instead. I suppose this pertains to coins if you have your 1894-S dime proudly illuminated on a wall in your foyer.

OK, this is probably blindingly obvious, but does that 28% capital gains tax get applied to the total amount of the sale or just the difference between what you originally paid for it and what you sell it for? If the latter, I assume that means it's critically important to keep good records of your purchases and that if you sell for a loss you wouldn't own any taxes, right?

My big problem is with bullion. Although I do have records of what I paid for various things, since so much of it is fungible it's hard to know, say, exactly which silver bar I paid $12 an ounce for and which one I paid $20 an ounce for. Or, worse yet, with the hundreds of junk silver coins I have accumulated over the years.

From the link Branmeister provided above (underline is by me):
"... The collector is considered an ultimate consumer and therefore has to pay sales tax on all purchases, unless they are shipped from an out-of state auction house or other vendor...."

In Florida, coins should not have sales tax collected. The state considers it money and money is not subject to sales tax.
I have been told this by several auction houses, one of which conducts the state of Florida unclaimed property auction each year.

(I believe ebay and other venues erroneously collect sales tax on coins as a precaution. IMHO, it probably won't be resolved until there is a class action lawsuit.)