Lawrence Schiffman has posted a series of brief articles on perceptions and mis-perceptions of Jewish purity laws of Second Temple Judaism.  If you want to gain better understanding of Gospel texts dealing with clean and unclean, these posts may give you some insight from a Jewish perspective.

• COMPARING THE DEAD SEA SCROLLS, RABBINIC LITERATURE, AND THE NEW TESTAMENT
• RITUAL PURITY AND IMPURITY AND THE ADMISSION PROCESS
• NEW TESTAMENT TEXTS

[UPDATE: I also see that Dr. Schiffman has another, earlier, four-part series, also dealing with ritual purity in Second Temple Judaism: Body and Soul, Purity and Impurity.]