One in four ads now feature a celebrity when only one in eight did in 1995, according to research from WPP-owned Millward Brown's CelebZ research.
This number is set to rise as media fragmentation and ad clutter forces advertisers to look at new ways to hold consumer attention.
Walshe, global account director at Millward Brown, said brands need to focus more on how celebrity behaviour affects brand values and urges brands to sign good behaviour clauses with celebrities endorsing their products.
"Shutting the stable door after the horse has bolted is not the best tactic for large brands investing millions in celebrity marketing deals," he said.
Since the tabloid revelations of Moss's alleged cocaine use emerged, H&M, Burberry, Chanel and Roberto Cavalli said they would not be renewing contracts with the 31-year-old supermodel.
Walshe also advises companies to apply the dynamics of brand values to their celebrity marketing deals.
"A wrong match could turn out to be a disasater, shaving value off the brand and impacting the bottom line."
Findings from a Millward Brown Australia survey showed that not all celebrities are good brand endorsers.
Australians liked Virgin boss Richard Branson, actor Geoffrey Rush and actress Nicole Kidman, but said they would be unlikely to choose a brand associated with Michael Jackson, US President George Bush, socialite Paris Hilton or singer Britney Spears.
Despite all the misgivings, celebrity advertising has considerably boosted sales for brands over the years.
Walkers' market share went up 6% when it started using England footballer Gary Lineker and celebrity chef Jamie Oliver added £1.12m in revenue to Sainsbury's, according to Millward Brown's CelebZ database.
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