Naw, if you are departing Philmont by train there is no reason to not have had at least one shower. The westbound train is in Raton late morning and the eastbound train in late afternoon. I figure - drag it out of bed half an hour earlier if necessary, the trip isnt over till you get back home so "sleeping in" is not on the agenda ;-)
The part about the day's activities, the school bus ride, loading your own gear and the natural funk of teenage boys is right on though. Even with a shower, by the time they settle in on the train they may no longer be fresh as daisies.
And, by departure day even the adults in the group dont necessarily notice when they (or we) are beyond fresh. Personally, if someone tactfully told me that one of my Scouts could use some attention, I would do everything I could to address the issue.
As we say at our overnight training sessions - this is "group living", everyone needs to be extra considerate, and extra tolerant, of others.