Enough has been said about bad treatment by border guards about every country on earth so don't need to repeat it but I had the following exchange with a Canadian visa officer.
Visa Officer:Your Name? How can I help you
Me: Dr XYZ. I would like to apply for a visitor visa to Canada
Visa Officer: Why would you like to go to Canada
Me: I have been invited to speak at a conference
Visa Officer: Hmm I see.
Me: Is there a problem?
Visa Officer: You see, you are not allowed to do public speaking on a visitor visa. You will have to apply a visa for public speaking which takes longer and requires additional formalities and checks.
Me: Oh, I see. I am surprised that is the case, I go around the world to conferences and it seems unusual in Canada.
Visa Officer: Can I ask you a question
Me: Sure
Visa Officer (with a smile): Would you say that your main purpose of applying the visa is to attend the conference and you will be sharing your professional and not political views.
Me: Yes. Absolutely!
Visa Officer: You should then get a visitor visa which will be ready tomorrow after 4. Remember, when asked say that you are attending the conference. Enjoy Canada
Visa Officer:Your Name? How can I help you Me: Dr XYZ. I would like to apply for a visitor visa to Canada Visa Officer: Why would you like to go to Canada Me: I have been invited to speak at a conference Visa Officer: Hmm I see. Me: Is there a problem? Visa Officer: You see, you are not allowed to do public speaking on a visitor visa. You will have to apply a visa for public speaking which takes longer and requires additional formalities and checks. Me: Oh, I see. I am surprised that is the case, I go around the world to conferences and it seems unusual in Canada. Visa Officer: Can I ask you a question Me: Sure Visa Officer (with a smile): Would you say that your main purpose of applying the visa is to attend the conference and you will be sharing your professional and not political views. Me: Yes. Absolutely! Visa Officer: You should then get a visitor visa which will be ready tomorrow after 4. Remember, when asked say that you are attending the conference. Enjoy Canada