Well, when it comes to Astredo, I pay very close attention
Indeed you do because to my memory all he ever wore was this gray suit (seen here in Ep #629 (in the scene with Diabolos), Ep #630 (in a scene with Barnabas), and Ep #631 (in a scene with Chris):
But lo and behold he wore a darker gray for his "marriage ceremony" with Maggie in Ep #632:
You will see the light brown suit in the episodes that follow the scene where Nicholas get's into trouble with the "D" man downstairs.
But if you can see a brown tint to any of those, you have a much more perceptive eye (or a better TV screen and/or computer monitor) than I.
Even the suit Nicholas wears in Ep #633_634, his last in the '68 storyline, appears to be the same one he wore in the previous episode to me (though the lighting for that show makes it appear gray, blue and even green):
Did we ever see the darker gray suit before Ep #632?
The next thing we know, a very devoted Robert Rodan fan will become a member and tell us that Adam didn't really wear the same green sweater in all those episodes after all. And if so, that would be a huge shock!