Should there be a minimum transaction limit to prevent dust spam? With all these reports of people receiving spam through dust transactions (e.g. Enjoy Sotchi, Bitwars etc) what would be the implications of setting a minimum transaction amount on the network? Why would anybody wish to send 1 Satoshi (0.00000001 BTC) it seems to have almost no economic benefit? Would such a limit disrupt any legitimate activity on the network?
There already is a limit of 5460 satoshi. It's unlikely any transaction smaller than this will be ever relayed or included in a block without colluding with a miner.

https://github.com/bitcoin/bitcoin/blob/b78d1cdf82fb12cc0c8eb9049074b359b9589b7c/src/core.h#L153