I never saw a freighter in any star trek shows so I only have my imagination and I think crptic did a good job making my ship. If Star Fleet or the Klingon Empire made a fast acquisition of a Freighter for a mission and used it afterwards I am sure it would be upgraded to their standards. The computers look dated to me and the rust would have to go. Star Fleet would make it look "spic-and-span" and this makes perfect sense.
There's actually quite a few freighters and their insides shown in the trek series.
Gul Dukat captained one just before he 'borrowed' a bird of prey from the Empire. 3/4ths of that episode is inside the freighter.
Mayweather (ST:Enterprise) has an entire episode dedicated to him when he visits his freighter family (he was born and grew up in it) during his leave time.
Neelix's ship is a small freighter.
and I think Picard also has a couple of episodes where he's in one.
The only time a freighter was shown as 'clean' was the Federation freighter owned by Mayweather's family. All others were stanky places...kindof like inside a klingon ship.