Upload & Sell: Off
From over 30 years of flying around the world I'd say:
a) Never put anything valuable in checked luggage.
b) For regional jets where you hand your bag "under the aircraft wing on the tarmac" and get it back the same way be careful another pax doesn't walk away with your bag by accident.
c) Prepare to be flexible (i.e if you see them weighing carry-on at check-in then stuff your pockets or hand off to a friend/partner)...they don't weigh at boarding.
d) Never be the last to board ...when everyone else has taken up every single square inch of storage space...that's a good reason for them to try to check your bag.
e) And my tried and true rule: The more frazzled the agent, the friendlier and more sympathetic you should be.
And far from standing up for Air Canada (who I don't really like), you should be aware that your luggage is handled by many different people other than their employees, including TSA agents, customs agents, airport workers, and employees from other airlines who may be contracted out to service your flight.
The same is true for check-in and gate agents. In many airports, especially in Europe, the airport supplies the agents; your airline might only have one or two employees supervising the flight. Depending on the country (and the culture) these agents may be tougher (or the complete opposite) in enforcing your airline's weight and carry-on rules.
Funnily enough the only inconvenience I've ever had was on a flight out of Montreal to Vegas with 40 plus lbs of camera gear...the security agent (equivalent of U.S. TSA) opened my bag and was so impressed with the array of camera bodies, lenses and other gear that he kept me for 15 freakin minutes as he gingerly pulled every piece out to admire it. Turns out he was a novice photog and was simply genuinely interested in all my gear!