it doesn't matter what color they are.

I would say about all you could do is remove the old system and open up walls and then refinish for were the new ducts will go.

She and her husband bought at the height of the market thinking the only changes they had to tackle were dated floral wallpaper and paint colors. 

I like neutral colors myself but in the pictures the colors in this apartment seem pretty, well, blah.2.

It's like  race cars; they look great on TV, but once you get close, you see all the dents, scratches, duct tape, rock chips, etc etc.

“Because the $20,000 took so much away from their equity to put into another home, they decided not to sell,” she said.Another client of Chaname had difficulty selling his home because would-be buyers balked at paying $16,000 more for a home with HERO-financed air conditioning, duct work, water heater and insulation when similar homes were selling for less.The buyers argued they were paying for the improvements twice – through the higher valuation on the house and assumption of the loan.

Its likely from all the standing water that it has started to rust out the duct work in the basement or grow mold inside it/throughout it (even on the upper level floors).Saw that recently on a property I looked at with 5 feet of water in the basement from when the sump pump backed up and overflowed (bank turned the electric off 3 years ago).

:P So I was just... doing... a thing... that I'm making up... as I go along... let's just duct tape this here, screw that into that other thing, use a little glue on the whatsit thingie, draw a smiley face on it for luck... and then I'm going to push this button, and then... boom, loan funded, deal closed, happy day. 

Patch and paint wholes..maybe paint whole house neutral color if they have funky colors6.  

I would not recommend doing the design part yourself unless you are extremely familiar with current trends, picking materials, coordinating colors, understanding product specs, and building code for that matter.