The "marshmallow effect" of so say is something that you only really get when a user use markings another user do not have. People using big marking packs for example will show up as marshmallows for others on whatever part of the body they applied this to.
However as explained above already, preset works like a skin above the regular preset less character, if other users do not have a certain preset downloaded either manually or by using preset sync, they will see the character just like nothing special with regular markings from the game if the character was made this way. If they would have another users preset downloaded however, it will just apply on top of the characters design made from the character creator.
So really, you just need to have a character made with markings and colors from within the game, and apply a preset on top of it. Everyone with your preset downloaded will see it with this, and everyone who doesn't will see you with the regular markings, no specific effort required on your part as long as you stay away from custom markings.
