as gloria rivera reports there are mistakes you don't want to make. this home in florida's exclusive pablo bay community checks a lot of boxes. fourn tans, really well kept grounds. a community pool, wide, clean streets. step inside and -- wow, this is crazy. >> it's a garage sale going bad. >> reporter: real estate agent todd arnold says this five bedroom house could go 40% below market value. >> for me as a realtor, you look and you go, this isn't going to help me sell this. >> reporter: real estate mogul and host of abc's "shank tank" barbara corcoran says even minor messes can sink a sale. >> when people see a mess, they think the boiler doesn't work, the plumbing doesn't work. >> reporter: a different kind of mess. this castle in chicago, and a drawbridge. and an eagle, that king arthur vibe? repelling buyers now for three years. >> you got to keep things simple when you sell your house. think of it as taking your money away. >> reporter: extreme cases, sure. but with lessons for all of us looxing to sell our own castle. how so you sell your home