Sundance,
Did you give any thought to common courtesy? The houses that you did not wish to visit had prepared for you and wanted to become better acquainted. You have snubbed them.
On your campus you will meet and interact with girls from those houses later. Perhaps these were not your "ideal", but I feel your actions were disrespectful. At least you should have contacted the Panhellenic organization at your college and sent regrets.
As one of the posters indicated you may have placed yourself in a difficult postition to obtain a bid, depending upon the rules of Panellenic at your campus.
I went to a private university with long established sororities and a strong Panhellenic organization. Frankly, even in an informal rush situation I cannot imagine a potential member ignoring an invitation and not appearing without some explanation.
