Huh? DOO means driver only
operation (the pros and cons of which can be debated in the dedicated thread, not this one) and has absolutely nothing to do with the inspection of tickets.
If a train has a Guard that doesn't necessarily mean your ticket will be checked (it may have a non-commercial Guard, if you travel with a TOC like Merseyrail or SWT, or the Guard may simply be performing other duties or not be equipped with a ticket machine, etc..)
If a train is DOO then that doesn't necessarily mean a ticket examiner won't be present. Ticket examiners/on-board managers are booked to be on all Scotrail DOO services, Southeastern Highspeed and are being introduced on GTR.
So, no, it does
not in any way indicate whether or not your ticket is going to be checked.
I'm sure you know this, but it does need to be challenged as some people may actually believe it!
If you - or anyone else - wishes to discuss the pros and cons of DOO, here is a link to the relevant thread:
DOO and related issues debate