I dunno, is behaviour really something you should have on the Contacts table ?
Could have Contacts and Good_Contacts and then just do a join. Although, guess it doesn't make much sense to have a table with one column. Suppose there could be a column for reasons.
Then again, SQL Clause may be into non-RDBMS
Edit : Also, that query might be slower than it should, index on behaviour isn't going to be as helpful.