My partner was testing a particular MDMA sample out of a number of test orders from various vendors...the reagents are supposed to be brand new, as they were acquired in the past week or two.... SO, on the batch in question... marquis went straight to black and fizzed......after a few seconds the outermost part of the "test puddle" was green. Sampled the gear anyways, and it was good. All other gear tested as expected for MDxx.
Working off sketchy memory here ie I could well be wrong, but I get the feeling that's a normal reaction with unwashed PMK-based mdma, the other reactions are standard with saffrole-based (or vice versa).
Regardless, I'm pretty sure it's a 'good' test and it's solid mdma.