Pugging can be a crapshoot, especially in lower keys. But it can be fun, as well. The vast majority of my experiences pugging M+ have been positive even if we didn’t always time the key, but it is true that you have no idea what you’re going to get.
Sometimes you get a great group of very good and nice players and double upgrade a hard key like it’s nothing, and sometimes you get people that are still learning and making mistakes. In my experience, it’s rare to get people who are very toxic.
If you’re going to pug M+ you MUST do it with the mindset that you’re going to brush off whatever happens.
Also, there’s kind of a truism that lower keys are harder and it really holds up. That range is by far where you’re going to find the worst behavior and generally have people making things way harder than they need to be.