I love, love loved Marc standing up for Betty's family, especially Justin. Marc is my favourite character anyway, but I thought they've always managed to show his human side without clashing with his essential bitchiness (I also adored his advice to Justin in an earlier episode: "Be who you are, wear what you want - just learn how to run real fast."). It wasn't like he had a huge change of heart, or was even going to be nice to the Suarezes to their faces, but his genuine appreciation for their kindness and his affection for all of them but especially Justin rose to the surface when his vile mother was nasty about them. It was made, dramatically, even better by the fact that his mother didn't do the heartwarming sitcom thing (a la Santos on the subway the other week - a scene which I did find very sweet, I might add) and Marc was soon back to being his evil self - on the outside, at least, although I think he and Betty both know that he does really like Betty, whatever he might say.
So yes, hurrah for a programme that manages to be kind and bitchy, sometimes at the same time.