or should I be able to swat you easily and without consequences if I happen to know a public tidbit about you, for example where you live?
Fortunately most of them contain a prepaid envelope, so I get a small amount of enjoyment out of sending those back empty, or with the outer window envelope stuffed inside...
If you don't like the spam, use Google apps/Gmail for your technical/administrative contacts.
It is fair and reasonable, if you are operating a domain, to be available for legitimate contact. I accept the small amount of money and time I spend receiving spam phone calls roughly once or twice a month, in exchange for the important notices and communications I receive (and can make) every couple.
But a random bot looking for victims it can spam shouldn’t be able to read all the WHOIS data.
It is public information, and it is impossible to watermark. There is absolutely nothing you can do about the scraping of WHOIS data if it maintains any of its current usefulness.
I own a .de, a .eu and a .info
I get hundreds of spam mails per day for the .info, nothing for the other two.
It works.
Technically, it's already in SOA record's RNAME field, which IMHO is a much saner option - given that whois is registry-dependent and doesn't even exist for some TLDs, and DNS is universal.
Well, no one can guarantee that it's working and mails will be read. Same as with whois data, of course.
Even for companies – PrivateInternetAccess’s phone number just is a robot saying "please send an email to the address listed in our WHOIS data" and hangs up.
The number of calls and emails was just stupid.