Avahi at 0.6.31 spews messages such as:
Mar 10 08:00:28 srv avahi-daemon[35097]: Invalid response packet from host 192.168.32.1.
which are mainly due to Windows clients sending trash.
To silence these messages, edit /etc/rsyslog.conf and add the line:
:msg, contains, "Invalid response packet from host" stop
right before the line:
*.*;auth,authpriv.none -/var/log/syslog
and then restart rsyslogd with:
service rsyslog restart