First off, I made a single post about the b&w thing directly and later tacked on a small "jab" (if you will - with a smiley, no less!) at the end of one of my posts. I found your post amusing in the other thread and I wasn't following you around trying to poke at you or anything.
Second, I don't feel that I have to prove anything, necessarily. I admit to being a little bit overly agressive and probably shouldn't have been. Perhaps I was trying to defend the Coens or something (and I'm not the only one that stood up; not even the first in fact). I am passionate about film and I have spent a good amount of time in it, BUT, I don't claim to know everything about it and I wouldn't even claim my knowledge of film to be vast - I could point you in the direction of a forum where there ARE people whose knowledge is what I'd consider vast, though. In the moment I felt your post was more or less insulting (not to me directly) to some highly regarded filmmakers and, as mentioned, probably went a little agressive. I should also point out that the original statement was that Raising Arizona was "really bad", not that it was "dumb" (where a dumb movie may not necessarily be considered bad, perhaps).
To outline, my feeling is that you didn't understand the film and thus you felt it was bad (and I'm not even going to say that I understand what they were doing with it, either - I also haven't seen it in a very long time and didn't spend a ton of time with it when I did see it). However seeing what a filmmaker can DO with a film, with the characters and actors, with his lights and colors, etc can be really illuminating. Ethan and Joel are masters at it. I want to point out (again) that a film isn't automatically bad simply because you don't understand and/or like it (though, in this case you liked it). I'd also like to encourage you to dig deeper into some of these films you watch - you'll likely end up enjoying them much more (Take O' Brother, for example; once you know that it's based on Shakespeare, you may find it very interesting to see what they did with the film and how they did it - it is interesting the time period they chose, etc).
For a reference from my own past, years ago I was not a fan of Kubrick at all. I didn't understand the big deal so I purchased the Kubrick box set that had 7 or 8 of his films. Once I'd finished I started to see why he was such a big deal. To this day, he's still not a favorite director of mine, but I DO like and respect his work (whereas before I didn't). Now, I realize that this is a little tangential to the issue at hand, but perhaps it can serve as an example of what you can do to further understand what you see (assuming you even care to, which is fine if you don't).