Read a thread on a truck forum a while back where a guy bought a Tacoma from an auction in Houston and found out three months later the frame was Swiss cheese. Said he crawled under it in the parking lot but it was wet from the rain so he couldn't tell how bad it really was. Cost him almost two grand to get it patched up enough to pass inspection... and that was on a Toyota, which says something given how those usually hold up. Point is even guys who think they checked can get burned if they don't bring a flashlight and a screwdriver to poke at it. That $600 deposit loss honestly sounds like the cheap version of that lesson.