My personal favorites? The one that was placed next to the 401(one of the busiest highway systems in the world), nothing like a pile of vehicle exhaust and hot asphalt to give accurate temperatures.
You mean the weather stations which are part of the Ontario road weather network, installed specifically to get weather information along Ontario roads?
<sarcasm>Yep, that was poor planning... </sarcasm>
The other, was out in Alberta which was in a valley, next to a river fed from mountain water run-off(roughly 4m away), which spent 2/3's of the day in the shade of a pine tree forest.
A provincial forestry weather station. Odds are it's in that specific spot because of either accessibility, power, or it's a known problem spot.
There's a lot of unofficial weather stations out there (easily 3-5x more than official stations), but they're usually installed for specific purposes (forestry, mining, health and safety, transport, etc). They don't have the same constraints as more official stations simply because the data they generate doesn't matter in the big picture.
The installations of official weather stations, in particular the ones which feed into climate models or get used for aviation, is a hell of a lot more rigorous.