There are several 4/5* courses I've played that I think are overrated, but if I had to pick a single least favorite it would be Hippodrome Old Glory by a mile. I would give it 2 stars, and this site has it at 4.07 stars. Just ... no.
Other modestly overrated courses are Richmond Hill (4.05, should be 3.0) and Tyger River (4.07, should be 3.5). Additionally, the Blue Angel Park in Pensacola FL is rated backwards. There are three courses on the property: Pines 3.81, Oaks 3.89, and Palmetto 4.13. The correct order should be Palmetto worst, Pines middle, Oaks best. (I think when I played there a couple of years ago the three courses were rated completely backwards. At least now Oaks has risen to the #2 spot.)