If you are using Windows 7 the you can use Resource Monitor to check your latency.
Type “resource monitor” into the start menu search field.
In the resource monitor application select the network tab at the top right.
In the “processes with network activity” put a check in the checkbox next to “gw2.exe”
Then look for the latency column in the “connections” panel.
That should give you a decent idea of your Guild Wars 2 latency.
Hope this helps