Part of the problem with Jedi is they went to the wrong desert.
Yuma just doesn't look as exotic as Lean's Jordan (or even Tunisia Lucas' favorite sandpit).
Most of the time we see Tatooine in ANH it's a real location shot, most of the time we see it in ROTJ it's a matte painting or a rather dull background plate with actors and models against blue screen and it shows.
Seeing as much of the location shoot was blocked in by sets and actors they should have gone out of their way to get more exotic background plates to frame both the models and studio footage.
Those elements don't really match the location shots anyway so they might as well have pushed the boat out.
Background plates don't have actors or vehicles so it wouldn't have cost that much to film and even some library footage would have looked better than some of the elements they used.
They were up against some bad weather but nothing compared to what Lucas had to face with ANH or TPM.
The real bad weather seems to have been in Lucas' private life which took away much of his love for Star Wars (not to mention the cost of Kersh taking the time to get things looking right the previous time around).