An informative article on ping vs latency by a Valve programmer:
http://www.bluesnews.com/articles/latency_vs_ping.shtml
"Ping is a simple round trip time for a message from one computer to another."
Latency is more complicated, and is affected by variables such as client FPS, server FPS, and server ticrate.
So the assumption that latency = (ping - 40) based on your respective values of 5 and 45 should not be generalized as a rule of thumb. In Zero's case, his ping was only 1 or 5 above latency. I've been accused of ping masking as well, although not by admins. I usually have a ping of around 5 because I live close to the server and have a fiber optic connection, but my latency is considerably higher because I often get 20-30 FPS in WCS, depending on map and player activity.