My first cut at this was to model the Bad Order card on the Empty Car bills I already have in use. The color I chose was salmon, a readily available colored paper stock, since I wanted these “cards” to be disposable paper and not cardstock. Here is the first result of this:
Experience to date tells me I have a workable Bad Order slip and it is now in use on the layout. I’ve always used some form of this kind of document, because filing them (temporarily) provides info on repeats of the same problems with a car. If appropriate, I then document corrections on the car’s maintenance page. (I maintain a loose-leaf notebook with a page for each car, and repairs or upgrades can be listed as well as problem corrections.)
Only issue I see so far is that the salmon color is not all that distinguishable from the pink perishable bills in subdued lighting. I will experiment with other colors to see whether something else works better, and if a color other than salmon is eventually chosen, I’ll post another message to report on it.