CBC are liars but I'd be surprised if Ekos is deliberately fudging numbers.

These polling companies make their money mainly from market research. That's where their bread is buttered. This election polling stuff is like a showroom event for them. It's where they get to demonstrate how much more accurate their polls are compared to their competitor's polls. They're all trying to be more accurate than the other guy because the more accurate you are, the more attractive you are to market research clients.

They're not going to sell their reputations out to give Trudeau a nudge in an election campaign. And if they ever got caught deliberately faking their numbers, they'd be fucking toast. And all it would take is one whistleblower from within the company to blow the lid off of the whole thing and bring the company down.

The cost to their reputations of being inaccurate (i.e. incompetent in the eyes of prospective market research clients who are their bread and butter), and the risk of them getting caught are just way too high for them to fuck around.