Getting rid of spammy links

[computergenius]

I just got fed up of links like this:
http://mysite.com/%5C%22http://spmsite.com/rubbish/

In my system, I have a custom 404, which sends me an email when pages can't be found, and the example wouldn't be found.

If a page isn't found, I need to look into it, but this rubbish just wastes my time.

Just to stop the messages, at the top of the custom 404, I said,
if the url contains a http like the one above,
do a 301 permanent redirect to my home page

Works fine, any spammers sending URLs like the ones above, are sending people to my home pages on my different sites.

But when I ask for the headers for the above page, I get 200 OK, and the home page. I hadn't thought about it, I wasn't expecting it. But the incoming spam links are now pointing somewhere useful!

So it looks like a win-win situation.

Any thoughts?