I was asked this question and also explain why it is detrimental to the android system as a whole.

I have not found a web page which refers to this specific question about Dalvik and swap space. Any links would be appreciated or an explanation.

What I have answered is 

Swap space is a method of using secondary storage of the device to free up RAM. This would not work on android as it is not guaranteed that a device would have secondary storage causing the application to crash. 

It is also slow to read from external storage as Dalvik is a JIT compiler this may lead to the code being compiled at a rate which is effecting the users experience with the app.