I think most people that play against me would call me a good player. I know there are many here much better them myself, but just want to baseline that in general I know that some decent players will sweat a little bit when we manage to run into one another (minus the times i go down in 2 hits

).
So saying that, I have trouble with swing spam. A better player is actually easier for me to fight with since they behave 'normally', while the new player that is suicidally swing spamming catches me off guard. I might try to do a feint on them and they just are swinging, and I get hit. It happens to me a lot.
But basically what I want to say here is you can't 'fix' swing spam. Here are the conditions that spam works and why (as far as I know).
***New players do not know weapon ranges and new players can not block. So if you are using a large 2 hander, you can often just swing as they run up to you, especially if you have a longer weapon. They will not block, and will probably try to swing at you. They will do this even if you have a longer weapon. They simply do not know that you can hit them before they hit you. Swing spam will simulate this.
****Big weapons will introduce weapon stun when blocked with 1 handers. I have this problem here, because in general with most weapon match ups you can swing immediately after a block and strike a person first. If you block a 2 hander though, especially if they find the optimal stun bonus (.6 sec remember), they can generally swing again and hit you before you return swing. I forget this a lot, and die to 2 hand spammers like a newbie many times.
But that is really the only thing a 2h axe has going for it, take it away and the weapon is hurt too much. Once you close on a person they won't really be able to stun you again.
***With good position, you can swing twice against a person safely. New players do not understand timing and think that you are completely free to just swing after a block. I think the game designers have done most of their changes to actually avoid this hit trading gameplay that existed early on.
***Click faster. I don't mean that condescendingly... m&b really responds to you clicking faster with better timing. When you play a really good player the thing you will notice right away is things happen faster, it is simply because their brain is ahead of yours, they are clicking and swinging/blocking IMMEDIATELY because they know what they want to do. Most players (myself included most of the time i'm not amped up) have about a half second of time between when they input commands while they think about it. Even a half second sometimes is enough to hit you first.
So really, I understand that people failing around, especially in crowds, seems like trouble. But eventually when the player base understands how to play, you will see this less and less. When you identify the spammer you simply have to stay facing them, block each hit and return swing. When it is a 2 hand axe back pedaling you have to think a little more but just remember to block and you'll get to them eventually...when you close you should be able to out swing them a few times to give them a taste of their own medicine.
Finally if you are still hellbent on finding ideas to defeat swing spam... try a search on the beta board (not this one) for swing spam and stamina bars, you will find lots of discussion that might give you some new ideas and insights.