The listing broker will love you for showing up solo and will probably push for your offer
Investor, there's just a little bit of logical inconsistency in your argument. If agents / brokers are all as "disreputable and dishonest" as you allege (backed by a noticeable lack of supporting evidence), surely one way you could begin to protect yourself, as a buyer, would be to have another agent acting on your behalf and only on your behalf under a Buyer Agency agreement, as opposed to going in on your own and putting yourself at the tender mercies of the broker who is acting for the seller? (The listing broker will be glad to "push for your offer" if it is unrealistically high.)
The wider question of how honest or how well equipped any particular agent is, would be a separate matter. As either a buyer or a seller, sit down and interview anyone who you might be thinking of getting to represent you. Also seek recommendations from others. Last but certainly not least, be proactive yourself, in looking at what is available in the market (as a buyer) or reviewing recent comparable sales (as a seller) and forming some of your own opinions, independent of what an agent is telling you and regardless of how good the agent might be.
As for "doing it yourself", without an agent, that's OK for the small percentage of people who are relatively sophisticated and knowledgeable in real estate matters,
and who have access to the full MLS data, not all of which gets on mls.ca. For the great majority of people, who are involved in real estate transactions only a few times in their lives, I will state flatly that doing it yourself is just plain foolish. I could recount a number of stories of people who have outfoxed themselves by not having knowledgeable advice.
(For anyone here who is wondering, I do not handle real estate sales and am not saying this to promote my own interests.)