I am a stickler for grammar. No, I'm not a perfect English major or anything like that, I'm just fussy about speaking right and writing right!. I don't always know all the words but I try.
Here in Singapore, we have a concoction of local vernacular words/ expressions mixed in with English - to become Singlish... (la, oi, eh ...ah.. makan (eat), kopi (coffee)).
I use it often enough but I am conscious of who and when I use it with, and always in informal, casual situations with familiar people. After all there are very few habits or characteristics that we as locals can actually call our own,
We are mostly descendants, some 3-4 generations ago originally from China, India or neighbour, Malaysia. My current generation is proud of who we are here, eventhough they are not really open about it as in waving flags and singing the anthem; but it exists and surfaces when talking points arise over national reps and sportmen.
While I am proud of the Singlish in a 'nationalistic' sense, I firmly believe it should not become more than that, an informal attribute and expression among locals.
But speaking properly should be a must have for oneself and for communication to the outside world.