Look at them for what? If it says verified/successful, and it's about that big... *Shrug* The missing data (files) weren't large enough to raise any flags (maybe 100MB total out of an 85GB backup) ... So it's pretty much a Perfect (oh shit) Storm of events.
If a year's worth of data suddenly drops off your backup you don't notice something is wrong? Or you don't think it's unusual when yesterday's backup had over a million items and today it's around 80% of that?
You will often need to change how your backup reports are configured since the default is usually either to log nothing - or everything. Unfortunately, most people have them log every detail - which is useless since it can easily run to hundreds of text pages.
But that still doesn't make them totally useless. As you pointed out, most have a file count summary and success/fail report at the end of the job. And I do eyeball for certain especially critical directories. I don't care if the office temp's 'furry porn' collection went missing. But I do worry when accounting or other important directories flag backup errors on half the files.
I had a client who was religiously backing up nightly and never checking logs. If she did, she might have noticed that starting six months earlier every
log was telling her nothing
had gotten backed up because of "excessive defective media sectors" on the external drives.
Another had backups - but they were all legitimately failing verification. Which the log dutifully reported.
Care to guess what happened when they needed to use one of them?
addendum: another thing worth looking at in the log is the job run times. If backup time is steadily or abruptly increasing without a corresponding increase in the number of items being backed up, that's a red flag. It could indicate hardware issues, excessive file fragmentation, or corruption of the backup system's database or indexes. All are things worth investigating before disaster strikes.