Losing multiple offers?

I've had some clients lose multiple offers over the last couple months. We've also received multiple offers on a couple of our listings ($350K-$500K range). A client of mine just sent me a question involving her friend losing a multiple offer as a buyer and feeling like something was "fishy". Have you been involved in a multiple offer on the buying side or selling side? Do you think the process went well? Feel like the good stuff is going fast and you're always a step behind?