its not all about how people talk (but stoner lingo can be important).. but you can also tell by -

+ how people dress (not always but sometimes .. the hippy look is probably the most obvious
+their movie collection.. stoners have a lot of movies that make you think and of course the key stoner movies ;]
+look at their pointer finger.. is the tip a little black looking from them pushing the weed in the bowl down when they are smoking?


i cant think of anything else now.. im pretty high at the moment. wee.