What is the average lifespan of a phono cartridge?

Here’s a question... what does a worn out cartridge look like...and better still...sound like?
if we all agree that just one pass of a worn out stylus will ruin your record, then determining that your cartridge is worn out...is going to cost you a record..or more.
Interestingly, to me, there must be numerous folks who are destroying their precious vinyl, precisely because they are altering the groove with their worn out stylus...and will not even truly realize this...until they play the same LP with a new cartridge...and hear the damage that they done...which is now irreversible.

@chakster
that is exactly right. I have a friend who has destroyed numerous valuable records that he owns while playing old SPU’s and other London’s etc., Poor guy didn’t realize that the stylus was worn out, even though the suspension seemed to be ok.The elliptical and conical styluses were so worn that after just one play the damage was done. He only recently discovered what he had done by listening to a new Clearaudio Goldfinger ---and then hearing the damage! Shame that somebody had strongly recommended the older cartridges and he followed their advice---blindly.

@bpoletti 

I don't agree. Once the groove is damaged, that is going to severely impact the SQ of the record, period. Just because your stylus is tracking a slightly different section of the groove...which may or may not be true, doesn't mean to say that the stylus won't be also tracking the damaged section...and that damage is usually pretty significant...and easily heard. YMMV.

@chakster 

that advice is not universal. Any stylus can be damaged and worn in far less time, depending on whether the arm is adjusted correctly, the overall treatment of the cartridge, and most importantly- the condition of the vinyl that is being utilized. A record that is full of pits and has dirty grooves will wear down any cartridge in a much quicker time. Some cartridges may last even longer than 2000 hours...depending on how they are treated, OTOH, the exact same cartridge may last just a mere fraction of that time.
Stylus shape is no guarantee of long wear.