Having written more than my share of software that attempts to retrieve the WHOIS info of people who submit their contact details to abuse.net, I can report from experience that the current thin WHOIS does indeed often fail to provide even the information that the registrars have. Thick WHOIS, on the other hand, is reliable and consitent.
Related note: the proximate reason to ask for thick WHOIS is to make registrar transfers work better. It is currently close to impossible to get the contact info from some sleazy registrars required to validate a transfer request. So for anyone who's opposed to thick WHOIS, in fact you're supporting the interests of those sleazy registrars against the interests of registrants, including individuals, who want to switch to a better one. If you counterargue that ICANN compliance should fix the problem, I agree, and while they're at it, they should require that registrars fix all the obviously bogus visible WHOIS info, too. Regards, John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. http://jl.ly