As mentioned above, there are various clues, even in just the domain name. And if the corporate entity chooses to be anonymised, you have to wonder why.
I started out in this lark via a Fidonet BBS with a usenet gateway, and we reckoned it would be trivial for a phone number anywhere in the UK to connect to a dial-up modem in Cheltenham. I remember one day when most of the sysops in the UK claimed to be running on a UPS because of a thunderstorm, all at the same time.
If you can't trust your sysop, who can you trust?