When you follow the price of redcans, mozelle and blackbox more than the stockmarket, and you know how much they are "worth" at your various destinations, taking into account whether it's pay week and what your opposition is charging.
When you start drinking redcans.
When you have been to the different communities so many times you have created your own scenic STARs and SIDs to alleviate the boredom.
When you figure out you can trim the company's bendy 206 to fly wings levels by hanging your headset bag with your half full water bottle in it on the control column.
When cigarettes are either winny red, winny blue (what!? taylor mades!) or whiteox rollies.
When you start eating at the community takeaway and don't get the trots.
When you wear out your second pair of size 14 double pluggers.