I noticed that the graininess of the shot of the Falcon leaving Mos Eisley has been addressed before here:

http://originaltrilogy.com/forum/topic.cfm/Star-Wars-Colortiming-Cinematography-was-What-changes-was-done-to-STAR-WARS-in-93/post/584251/#TopicPost584251

A possible culprit being a pair of pantyhose over the lense!

The shot is very grainy and dark/dusk-y on GOUT too but it does not look "dirty". I don't mean dirty as in dirt and speckles on film, more like as if it is projected on a dirty, nicotine-stained wall or something. The sky looks like it is made of blotches of blue and brown. I think there was a clip of Luke in the speeder that had a similar "brown grain" look to it.

It only stands out in 1080, anything less and it sorta blends in, giving a nice warm feel to it but in 1080 it's a bit obtrusive.

Oh, and regarding the "stilts scene" with Luke and Ben walking in Mos Eisley, it really is blown out. The wall on the right-hand side has more detail on GOUT and at the back you can see a cyan/magenta sky through the two corridors instead of the white/off-white background we see in team_negative1's clip.