Here's a question. My Mycellium wallet received some of these Enjoy/Sochi spam/dust transactions for 1 satoshi each that have been going around. However, not enough fees were included in these transactions so they will likely never confirm.

http://www.reddit.com/r/Bitcoin/comments/1xin5m/suspicious_lots_of_bitcoin_wallets_just_received/

If I now send an outgoing transaction from my wallet, is Mycellium smart enough to not use inputs from these unconfirmed transactions? If not then we have a denial-of-service problem because I will have generated a transaction that will be stuck and also unconfirmed.

This is exactly the behavior I saw happen in my Electrum wallet today as well (which did try to spend the input from these spam/unconfirmed transactions) and it sounds like their developers will be fixing it.