Yup, have been in so many of these situations and each time, the only way I've been able to deal with it and prevent a full-on meltdown is to just remove myself from the situation.
Those who tell you to just "deal with it" obviously don't suffer over-stimulation problems. I think the only mature way of dealing with it is to let someone walk away when it's getting too much and don't judge them/ criticise them since a melt-down is much more dramatic and difficult to deal with/ manage.
I have a huge problem with scents, particular smells can easily send me over the edge, so I tend to avoid places like restaurants, and especially the meat section at supermarkets because of the use of chlorine and other chemicals.