How does any other self-employed individual secure a mortgage then, without a paystub?
This is exactly true. I have been operating as self employed without any hassles from lenders. And yes, will be paying my taxes this year too.
I just bought (and financed) a brand new car (yay!

), and not a shitty one either. I was a bit worried at first about the financing because even though I have the means to easily make the payments, I had no "paystub" to prove income over the last year. I do deposit all of my cash into bank accounts for safe keeping, so I knew that I had some way to prove that I have regular income, if necessary. I applied for my financing as "self employed" with my estimated annual gross income. Upon the credit check showing a strong credit history, I was not asked to provide any more info or documents, and was easily approved to finance the full amount of the car.
Mortgages are obviously a larger thing to deal with, but assuming that one claiming to be self employed is paying taxes and has a good credit history, I don't see how it would be any different from any other self employed individual in any other sector.
Of course there is many reasons for the decriminalization/legalization of prostitution, but for serious SP's who consider themselves as business owners, these kinds of financial issues are not something be concerned about, from what I have seen so far.
As for taxes, the CRA is not a law enforcement agency... They don't care where your money came from, they just want it!