you might not be able to trade that coin due to a thing called blacklisting, or censorship by miners.
It should be noted that this is a theoretical risk. As far as we know no Bitcoins have ever been blacklisted in this way, and with almost certainty we can say that no coins have been censored by miners in this way (the level of collusion required would be very high, and it would probably become public pretty soon if it happened).