The 7d has a pretty advanced 19 point AF system. Highly accurate and very precise, but this also means it’s more difficult to master.
I don’t think you have a lemon, and I don’t think 99.9% of the others claiming to have a lemon, have a lemon either.
I had a hard time learning auto focus with my 7d and just when I thought I had it mastered, a new technique would get me pulling my hair out again. lol I’m very very familiar with all the 7d focus talk, and spent way too much time reading about it, and wondering if my camera sucked, when I should have been reading my manual.
Yep, it was the person behind the camera making all the mistakes 😉 and once I saw that it was me, and not my camera, I went back and read those same forum and blog posts, and realized it was also the case with everyone else with a focus problem lol
You’ll find this type of thing with any camera model or any lens if you’re looking for it. People LOVE to blame their equipment. It’s not just the 7d’s problem, there are billions of so called “lemons” out there 😉
Here’s what I suggest. Go through your manual and check out the AF pages (most worn out part of my manual) extensively, while testing right as you go along so you completely understand each and every option, setting and technique and how to use them before moving on to the next. Use everyday items, pets, kids, whatever you see. Do test shots, use a tripod for the control to find your lenses sweet spot. Take your time a delve into it. Boring, but oh so satisfying.
It’s worth it. I finally was in control of my camera instead of it controlling me, and once I took my time with it and understood, I never had a problem with focus ever again, and had people coming to me asking how a achieve such sharp selected focus (YAY) You can do it, and be just as thrilled with the 7d’s focus performance as everyone else who has taken the time to learn it.