im interested in buying a 05 xb i currently have a tc,

when i took the xb on a test drive i notice a aggravating road wind noise from the hatch area...

is it a common issue with 1st gen or maybe it was in a minor accident in the rear.

No, there is no hatch noise. There is a strange XB idocyncracy that causes an extreme HARMONIC DISTURBANCE when the rear windows are down at highway speeds. As I recall even partially rolled down rear windows will allow wind to make a noise like a bottle top wistle.
Were your rear windows down?

It is all in the vehicles aerodynamics, or lack there of.

Simple solution, Turn the radio up

Deaden the hatch with the right tools. A good solid layer of butyl sound deadener, a few pounds of polyfill, and a closed cell foam cover between the hatch cover and hatch. It will make all the difference in the world. Keep in mind, once you have the deadening bug, it's hard to stop.

mine is pretty quiet...unless the kids are back there