Dave / Vern, ....Perhaps there is a 'Simple' Solution - to help stop this rampant Fraud (if there is such a thing!) - which will help to solve this Problem:
(1) Given that:
a) The GDC Site is Open & input is 'transparent' - except for the IP Addresses, which can be easily changed ... by switching to another Computer...
b) We 'need' to be able to communicate with one another on the Forum, so Email Addresses & PM functions, are very valuable to ALL members...(& should be preserved)
So, a step in controlling 'Scammers / Spammers' like Pawel Nowak and Sylvie Salter, et al, could be a simple as your Adding a 'Locked' Thread, @ the very Top of each individual Forum (using a different colored RED sticky designation) and titled as "BEWARE ..of ANY UNSOLICITED OFFER" or some similar wording.
Then you add in the appropriate wording, as has been suggested elsewhere - to serve as a permanent Reminder & Constant Warning of vigilance to GDC Members - much as you have the 'Rules of the Road' posted in each Forum.
(2) Also, I'd suggest adding a FRAUDULENT DEALER / SELLER FORUM ... where we can Post the details of the various types of Selling fraud which have been post in this thread, as well as in the SS Dagger Thread ...SS Henkels RZM, regarding Sylvie Salter. The FRAUDULENT DEALER SELLER FORUM .... would be a Forum to consolidate ALL of the Fraudulent Threads into one (1) spot where GDC Members could check to identify the 'bad' guys. If there is contradictory information, the Seller would be able to add his 'version' of the Transaction, that went Bad.
I want to see GDC remain 'open' and unrestricted - and this Suggestion allows for same.
Thanks for your consideration ... Dave ...dblmed
