The waters can get pretty choppy inside the celebrity fishbowl, and often it is hard to distinguish between who is swimming and who is sinking.
However, there is one barometer of one's ''star status'' which is more reliable than most: the prices generated by their paparazzi shots.
Take Lisa McCune, for example.
Formerly Australia's sweetheart, a photograph of her lying in a park six months ago would have barely raised an eyebrow, let alone opened a purse. Fifty bucks tops, but maybe a little more if she had piled on masses of weight or was topless.
But when shots emerged showing McCune, a married mother of three who appeared to have it all, cavorting about with her hunky South Pacific co-star Teddy Tahu Rhodes, suddenly McCune was hot property again. The racy shots fetched about $50,000.
But that was just the beginning. Other images showing McCune and her ''bad boy'' co-star have made about $250,000 in recent weeks for a small band of paparazzos who have been following her.
However, it seems demand has waned, with the most recent set of shots sold to a Sunday tabloid for about $500.
While plenty of noise is made about the massive amounts of money earned for ''the money shot'', it is actually the mundane shots of famous people going about their daily routine that are a local paparazzo's bread and butter.
This week, PS received shots showing Mel B jogging ($150), Ronan Keating with his kids ($150) and Sonia Kruger attempting to appear clueless about the lenses focused on her as she swallowed her lunch at Woolloomooloo ($100).
Interestingly, in the cases of Mel B and Keating, they each published their movements on Twitter earlier that day, resulting in a guaranteed gaggle of paps turning up to document their prosaic activities.
That's exactly what the stars want: control.
It's the shots they have no control over that cause them the greatest angst, and quite often, embarrassment. Just ask the Duchess of Cambridge.
Like all industries, it is simply an issue of supply and demand, as PS was reminded at a Friday lunch not so long ago on Woolloomooloo's celebrity magnet, the Finger Wharf.
On a quiet Friday, it's the Finger Wharf where the snappers of Sydney lurk, hopeful of getting a decent shot of a celebrity having a long lunch and getting a little playful after a few vinos.
If they strike gold, they will get a star of the calibre of Lady Gaga smooching with her boyfriend and a $5000 pay-off.
Nine times out of 10, it's just John Laws and his Princess, and a lousy $100, though his shots could have made about another $50 in the wash-up following his Wild Turkey interview with the ABC's Leigh Sales.
On one occasion PS witnessed Tania Zaetta promenading up and down the wharf. While there were plenty of photographers about, not a single shutter clicked.