It is the one thing I have learned the last few years of brewing. If my gut reads something is wrong when I check invariably there is a problem that needs to be corrected.
Case in point I brewed a beer last week and a few minor things stick out in my mind looking back. That pump is running a little louder-harder than normal. The grain bed seemed to settling higher and odd position to normal. My gravity during mash out was lower than normal. Looking back at all these little things they clued me in there was a problem but I didn’t know exactly what until it was too late. We get our grain pre-milled, a shipment didn’t get milled, or crushed, properly so when I went to empty the mash tun I discovered that fact. From now on I will double-check each bag of grain to make sure it has been milled. Thankfully it was the first of a two batch session so I was able to compensate on my next wort and even them out.
If you didn’t clean it, assume it dirty.
If you didn’t check it, assume it didn’t get done.
In the end you have to remain mindful of your surroundings not just to get the job done right, but also safely.