Visually detecting a rear main seal leak?How?

For those of us who have never had a rear main seal leak, can you tell me (us) how do we discover we actually have one. I got under the car and oil drips are on the oil pan drain, inspection cover hole, starter, splatters on the exhaust pipes and the A833. I have double-checked all valve covers and intake for leaks...zero. Thanks for the info.