I’ve been doing this for a while now, I’ve also critiqued quite a bit of performances and performers because I do believe that is how I can get better at improv; I watch others to see the things they do that I like and want to mimic or that which I don’t and try to conscientiously avoid.
I like to look at improv in two ways. First as a discerning audience member to whom improv is just another form of theatrical entertainment and with no improv background. The other as a technical performer. Most times though, my “audience member” will win.
That being said, I’ve started to watch improv people in the audience as well. I see where they are in the watching process and am usually surprised to find a correlation with where they are as an improviser.
It is interesting watching people watch a show and critique certain aspects of it that I don’t find as irritating because I see more than that one problem that, that one performer has. Don’t get me wrong, everyone has problems when it comes to improv (me included) but that is when it becomes more important for group cohesiveness. Because if you like the people it makes it easier to accept both the good and bad.