The scenario you show would be a legal short sale. If you have a margin account, Ameritrade would borrow the stock and lend it to someone else to sell short. In that person's account, the shares would be marked as short position. If he sold them to someone with an E-trade or Ameritrade account, the buyer would not know (and wouldn't need to) that those shares come from a short position as they are real shares. However when you sell your shares, Ameritrade would have to return shares to your account by either borrowing them from someone else or forcing shorts to cover.
You can find the number of shares legally short in SPNG at OTCBB.com. Those numbers are usually very small as it is very expensive and difficult to short pennies.
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