I think the so called "reciprocal link penalty" real estate sites are talking about and what was discussed extensively at
SEO Moz, REW, and even Matt Cutts blog a bit is a penalty for link networks. The reciprocal links were done through HUGE networks of sites that had multiple state pages that were nothing more than exchanged links. These were done on a gigantic scale and I believe many were done through automated programs or link networks. They were not your garden variety link exchanges that simply pass value. They were huge networks obviously designed to game the engines. Yahoo punished them first and Google followed suit. There is no reciprocal link penalty but there are penalties for link farms and the like.