People on a first date don't need much time to know whether they'll want a second date. According to a new survey of 2000 people, the average American needs only 19 minutes on a first date to tell if they're interested in seeing the other person again. The most important thing people said they look for in their date is manners (51%), personality (48%), conversational skills (47%) and physical appearance (44%). Conversation topics like old relationships and religion are a major no-no. Other common roadblocks to a second date include things like clinginess, poor hygiene, lack of a sense of humor, being too obsessed with your pet and being too negative.