What is "DBus.Error.AccessDenied: An SELinux policy prevents this sender from sending this message to this recipient" ?

Issue

• When running Red Hat Enterprise Linux (RHEL) 7 in SElinux mode permissive or enabled various errors show up, like:
  • "DBusException: org.freedesktop.DBus.Error.AccessDenied:An SELinux policy prevents this sender from sending this message to this recipient" in journalctl -xn output
  • "systemd-logind: Failed to get system D-Bus connection: Access denied" in /var/log/messages
  • " subj=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 msg='avc: denied { send_msg } for msgtype=method_call" in /var/log/audit/audit.log
• Why am I getting ABRT message at login showing "org.freedesktop.DBus.Error.AccessDenied"
• systemctl --failed shows lot of failed services
• Disabling SELinux seems to solve the issue, but when switched back to enforcing or permissive the issue is back despite relabeling
• tuned start failed at boot, starting it manually fails, too