I also don't read twice. Ain't nobody got time for that.
The article seems to be directed at people who've never beta'd before, and I suppose that's its focus, so fine. But a lot of it was either kind of obvious (e. g. learn what the terms mean, don't take stuff personally).
It did not go into what is probably a better means of critiquing, which is the ole shit sandwich. E. g. more or less pleasant stuff to start, harder stuff in the middle, pleasant at the end. Not to damn with faint praise or lie, but to not tear someone a new one. A beta reader who is too harsh is just going to make someone dig their heels in all the more.
I would also suggest appealing to an authority if necessary. Grammar Girl or the Chicago Manual of Style, that sort of thing. I recently did this with a guy on Wattpad - sent him a link to an article on dialogue tags.
If a work is really dreadful, I usually tell someone I am not the audience for the piece. I mean, unless it's out and out plagiarism, it's somebody's baby. I also try to find something to latch onto. For another Wattpadder, I really didn't like how clichéd a story felt, but I did like a supporting character. I suggested a second story featuring that character, who was a lot more original and was created well.
PS This is more about how to work with a beta reader if you're the writer (in the interests of full disclosure, I wrote this post):
http://lonely-writer.com/working-beta-reader/