Companies like this give me the ick

Irrelevant. If you want to lessen the amount of shit you ask your employees to clean, you allow fewer people that lack respect for your facilities. Your own warehouse employees fall into the mandatory admittance category. Outside carriers fall under discretionary admittance. After the fourth or fifth turd scraped off the ceiling, it maybe just becomes easier to send them to an outdoor toilet or to the truck stop down the road. It’s a great excuse. Not like they need one though, given it’s their building and all.