[jakecraige]

It's not so much that miners would ignore empty transactions, it's that the spammer would need to pay the miner fee to get each transaction in the block which would end up being very expensive and unsustainable long term.

For the second idea, this wouldn't really work either. When each node receives a transaction it will validate it first before broadcasting it to other nodes, so it would be stopped from propagating through the network pretty quickly and no one would attempt to include it in a block and run do PoW work it which is the most time consuming part.

I suppose in theory if you had a large enough network and could target a ton of nodes individually you might be able to do some form of damage but that's likely a pretty impossible amount of power and similarly to the previous example you could maybe bloat it a bit but it would be very expensive to sustain an attack like this.

[marmalade92]

the 2nd idea. But in order to validate if I actually own the money it has to traverse through the history. Now, I do not know how fast that is, or how far back it goes. But if it has to check and lets say it takes X amount of time, the spamming it will flood the validation without requiring a fee?

In general the 'attacks' are possible but expensive. However are they government expensive bulletproof? especially if we target less expensive coins aka alt coins.