there are a number of reasons people can be denied entry. do some research and make sure you'd get in. arrests/convictions for violent offenses (even old) can do that. talking to a canadian lawyer would not be a bad idea.
some things that people have said are key to admission as a long-term tourist:
-be able to prove you can support yourself - bank records are good
-lease with end date or with future travel plans to exit
DUI is a felony in canada and is a no go if you have one
There are some interesting things I have found regarding time limits and the tax code, but I have to admit I got really excited when I was reading this and realized how easy it would be to just go on a trial run for a few months.
I really think that is what I am going to try and do at this point. Maybe make it for WCOOP or something. But overall it just sounds really kickass now that I know how easy it will be just to try!