what people have to relise is there IS NO BEST WAY. Its a matter of experience, not something that your going to learn from a web discusion board.
Every time something is posted in response to a question the answer is limmited and probably does not cover every aspect of the topic. Hence missunderstandings occure and people can possibly be hurt.
With the above in minde: Squashing the stem is a good way of bruising the mushroom. As is breaking the stem, scratching the stem etc. Usualy the edges of the gills have been brushed by some object already and some bruising can be seen there. The Bruising is VERY pronounced and could not be mistaken for any other colour. The time the bruising can take to occure varies. Other poisonous mushrooms also bruise, most a black colour but some blue (This is heresay as I have not see such a mushroom but I do beleive that it occures). So be very carefull