I agree and just wanted to emphasize that although they do set high standards for visitors married to Canadian citizens, that does not mean it is not possible.
Also: it is absolutely NOT true that there is a policy to deny visas to all spouses of Canadian citizens. They are clear about the policy: it is to deny visas to visitors who are likely to not comply with the stated purpose (i.e. visiting, not staying) of their visa.
Unfortunately the reality is that there is a huge overlap, i.e. many visitors married to Canadians do overstay. So yes, chances are indeed low and the bar is high to get visas in many circumstances.