As far as I know, "working out" with no or not enough cardio can actually make them appear larger, because muscle will develop under the breast tissue. This is why one must remember to include cardio in their work out routine. There is no such thing as "point weight loss" (the assumption that doing sit ups will make you lose weight in your stomach-- it's untrue, and the same applies to the chest). Strength exercises can only really make things bigger (building) or tighter (toning). The only routine that contributes to fat loss is cardiovascular exercise (running, swimming, biking, stairstepping, jogging, dancing, etc).
I struggle a lot with clothes myself, and I don't even have a noticeable chest. Most people tell me they can't see it, but that's because I wear special combinations of clothes to mask the look. It limits my wardrobe to about 3 different "types" of combinations (I have variations in colors and such, but not styles). I can imagine for larger guys that this could be a more serious problem.
Halloween is a struggle for me as well... I have very limited options this year.
