Painted parrot cages would definitely look pretty but paint may peel off and eating it could be detrimental to the parrot inside. However, if birds cages are painted by powder coating with dry paint, it may not do much damage. Since the powder coating system makes the solvent of the conventional paint redundant, and bonds the paint chemically to the metal, there is no risk of the paint peeling off.
While horizontal bars are generally recommended for all bird cages, it is a must for parrot cages because parrots climb through horizontal bars, using them like steps. The spacing between the cage bars should not be more than half an inch except in the case of birds, which are very large.