Terry pretty much hit the nail on the head.
Shana pugs are more for seeing how much pain you can sift through to play a game considering the small community at times of day. Asiafortress pugs will net you better games on and off for the reason that Vetia has pointed out.
Best quality games are either in scrims with more dedicated players or mixes
To some extent I unfortunately do not completely disagree with terminal especially since he played a lot of Shana games. The overall player base is not amazing and this carries the feel into ugc as well (asiafortress seasons tend to be the bigger and more dedicated seasons of comp over here). Though I prefer if he played against others up the tree before forming that opinion.
In ugc for both 6s and hl there are generally only 1 or 2 "super teams" you look out for each season if you plan to win with the rest not really at the same level.
Also for the most of SEA we are plagued with routing issues regardless which part you are in, so much so that most dedicated players invest in a vpn.
Koreans have a dedicated HL scene, there is a small Taiwan 6s scene that I do not have too much experience with and the japs and Chinese have their own groups as well.
Playing to Australia is difficult (120 ms range maybe some packet loss with Von from Malaysia as an example) playin to eu may be impossible consistently.
Hope this helps and feel free to approach me, vetia or others for info