It is very easy for a prospective employer to verify someone's claim that he or she is a VCDX. The official VCDX directory hosted on vmware.com, http://vmware.com/go/vcdxdirectory , is complete and authoritative. Anyone not in this directory is not a VCDX.
(Incidentally, I am aware of attempts at "volunteer," unauthorized VCDX directories. Regardless of how well-intentioned these efforts are, the program does not support them, for one simple reason: there needs to be a single authoritative source of data on who is a VCDX. If you are a VCDX, and someone asks you for information for inclusion in a "volunteer" directory, I suggest that you decline.)
If you search for "VCDX" on career repositories such as LinkedIn or Monster.com, your results will include some people who are not VCDXes. One large subcategory, especially on LinkedIn, will be recruiters who want to hire VCDX-qualified personnel. These listings are easy to differentiate from claims to hold VCDX, and confusion is unlikely.
A very small subset of "VCDX" search results will be people who are genuinely making a false claim to hold the credential. Fortunately, this kind of attempted deception is rare, probably because it is so easily detected. Nevertheless, any prospective employer is urged to consult the directory whenever a candidate claims VCDX. When VMware becomes aware of these claims in public forums, we make efforts to see them removed.
The rest of the hits on the string "VCDX" will come from people who participated in the VCDX3 program, several years ago, but did not make it all the way to the VCDX3 credential. At that time, the prerequisite to attempting a VCDX panel defense was to pass two special-purpose exams, the VI3 Enterprise Exam and the VI3 Design Exam. A few people who passed either or both exams are touting the fact on their public job profiles, calling the exams something like the "VCDX Admin" or "VCDX Design" exam.
I assume that the people who are doing this are not deliberately trying to mislead anyone. Rather, they're probably thinking, "Hey, I passed this exam, and it was en route to VCDX, so why shouldn't I describe it as a 'VCDX exam'?" There are two reasons why this action is hazardous to the candidate:
I encourage anyone who passed the VI3 Enterprise or Design Exams to replace that fact on their curriculum vitae with the news that you achieved VCAP-DCA and/or VCAP-DCD.