I did wonder about that but I cant recall if I even used a soap and if I did I rinsed it really well.
I've got mixed seed in there but I was thinking of seeing if I could tempt them back with sunflower seeds as they do love them best.
I tried fat balls but the squirels finished them off in a day *sigh*
Maybe another full rinse out and some sunflower seeds will do the trick. What pampered birds!