I was working with HAProxy today and I couldn't get it to validate the server but I did find hundreds of these in the access.log.

192.168.56.200 - - [06/Nov/2015:01:38:08 +0000] "\x16\x03" 400 0 "-" "-"

The problem was that I have the following set in my backend section without SSL enabled on the hosts it was checking:

option ssl-hello-chk

I deleted the option and everything worked smoothly after that.