First of all, no anti brags at all. It is very rude to anti brag an adoptable. The artists and I work very hard and it would make us sad to see an anti brag. Any Dragon being anti bragged will be reposessed and given a new owner.
Secondly, don't disagree with a brag. You don't need to gush over the adorableness, but if you have nothing nice to say than say nothing at all.
Thirdly, be sure to include an image in your brag.