I once saw a facebook page that had stolen work from many artist (who watermarked their work well) and I could identify who made each cake. Two things stood out for me 1. work can be stolen even if it is watermarked and 2. Each person has a unique style. If someone steals my photos I say great, reproduce the work to the same standard or better and don’t disappoint the customer. Most times the work that is stolen is well above the skill level of the thief, otherwise they would show case their own work.
I agree totally with Jennifer and Clever Little Cupcake.