I use Maya to create many of my models. When I export a model with a Boolean Method used in it, however, I get an error. This is caused by a failure of the exporter (COLLADA) to export null values. I can open these models in the Editor and remove the extra models that occurred because of this error (All subtracted objects appear as normal objects) and the model is as it was in Maya. My question is: What is causing this?

It's been a few years now, but I was instructed by a college professor of mine that boolean methods and game engines in general, don't play well. He always advised to avoid them, but if you use them to be sure that you delete the object's history, freeze all the transforms, etc etc before trying to export them. I have found that Ctrl-D duplicating an object and using that object seems to clear out some hidden unwanted/unused information as well.

I am not experienced enough with booleans (his warnings made me steer clear of them) to know/verify with certainty his belief, but generally, deleting the history/using a duplicated model tends to solve that stuff.