I realize the sensitivity of this particular issue, so I'll tread lightly.
Hopefully someone will back me up on this, but...... there is a distinct difference between someone who is overweight and wears regular clothes that may show some excess flesh folds (but within the clothing) and an overweight person who, for whatever reason, purposely will wear a too-small t-shirt or tank top that doesn't cover over their belly so that others can actually see their flesh sticking out or poking through the gap between the bottom of the shirt and the top of the pants.
The nasty part is seeing the actual flesh, not discerning the flesh which is covered up by a properly-sized shirt.