What do you mean? There are allophones of /t/, yes... At the end of a word (if nothing follows), /t/ can be pronounced in three different ways, as far as I know: 1) Released: you can hear the /t/, which is sometimes aspirated to some extent 2)

Hey! That's a little tricky. You can say CAN AS /kæn/ and kɛn as weakened, but you can pronounce the negative the same way in fast speech. all depends on the context. That's the reason you sometimes hear "I can't do it the same

No! It's not sloppy! It's actually advisable to pronounce BUTTON that way in American English, since it seems to be the most common way to pronounce the pair NT. And the same goes for similar words: sentence, mountain, cotton, etc. The T