I purchased some from ECX and it tasted a bit odd also. I ordered some from HDV and it was what I was used to.
I have gotten a bit leery about ordering from distributors who
buy in bulk, then break into smaller containers. I can't help but wonder how fresh the flavors are. Am I getting the last 10ml from a liter bottle they bought many months ago? Profit margin will motivate them to
buy very large sizes, reducing their cost per ml. But, if they guess wrong on demand, they'll be shipping from that same bottle months or (gasp) a year later. When I see a flavor at a special price, I wonder if they're getting rid of the dregs from the bottom of the bottle.
Having a distributor who carries multiple brands is certainly more convenient and reduces my shipping charges. However, I wonder what price I pay in freshness for this convenience. And, I use a wide variety of flavors, most of which a 10ml bottle could last me over a year. If the flavoring is already old when I first get it, it'll be stale after I've only gotten a few months out of it.
Can't criticize the distributors. It's not practical to expect them to dump half a liter of flavoring because it's getting stale and hasn't sold as well as they expected. But, I'd love to be a fly on the wall at their facility and have an idea of exactly what I'm buying.
Oh well, not sure what the solution is to this. I believe (or at least guess) that in the chemical industry, lots are tracked and whenever a drum is broken down into smaller shipments, each smaller container is marked with a lot number and date code. Probably too much to expect a flavor vendor to adopt that policy.
I guess my whole point to your post is that I wager a guess that you got 'old inventory'. Just a hunch.
P.S. - full disclosure. I recently purchased some Hangsen flavors on special from ECX and they tasted excellent. I hadn't bought them before so I don't have a point of comparison. Regardless, the mixes were very tasty at the normal Hangsen 6% I generally use.