I never had TAs in high school but my college TAs have always been either really helpful or pretty bland, none have been awful or incompetent. I find it they tend to be a bit more excited about their jobs than my professors because they clearly haven't been corrupted by the job just yet.
If I get into a master's program this year I'll probably end up being one so I can't rally bash them.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"