As a man with a decent sized wardrobe of shirts, I have experienced bouts of looking at my shirts and realise that they are no longer wearable. Here are the following reasons:
The collars show a white fray...
...especially on coloured shirts and my stripes collection. It's ugly and yet it took time for my eyes to capture them. Why? Men like me do put my shirts on in a hurry and don't do a visual inspection when we put them on. It's only true friends (male and female) and hopefully colleagues who point it out to you. Embarrassing the least. The shirt collars have been victims of tough ironing at high temperatures and too many wash cycles (normal wear and tear). I figure a favourite shirt which is worn at least once a week cannot last more than a year? It's harder when you have a white shirt because it's harder to detect the fray.
Ring around the collar?
Sounds familiar it's a combination of sweat and bad washing. this one is a real obvious faux pas on a white shirt. Again a caring colleague or friend would point it out. But it's a really sensitive subject unlike lipstick on your collar. You'll need a new shirt really quick.
The cuffs are the victims of the same treatment as highlighted above.
It would be easier to fold your sleeves up to hide things but you'd look really out of place in the office. You don't need colleagues or friends to tell you this because you can see your own sleeves.
Getting your shirt destroyed by a leaky pen.
That is really a point of no return because no amount of washing will save the shirt and many colleagues and friends will point this one out right away. An accidental squirt from a fountain pen is something from the past but if it happens to you then say goodbye to that shirt too. Food squirts still have some redeeming solutions but chilli crab and laksa are tough ones. Case of bibs is really in order for seafood dinners and laksa joints.
Buttons are also victims...
...but more so from threads that go awry from many washes and domestic help that forgets to retrieve the missing buttons. Some tailors (the good ones) will have a spare sewed near the hem of the shirt at the tail end. If for some reason you have a zipper on your shirt then you could lose it all with a faulty zipper. Rare but worth a mention.
A disposable attitude. Men suffer a lot from that because they are not such detailed persons in general. SO they don't look after their shirts and they don't do visuals on early warning signs. It's hard to change attitudes unless it affects their bottom line. A favourite shirt is still a favourite shirt but loses its value with a disposable attitude. Learn to like your favourite shirt.