It's the fear factor that hinders execution of most great guerrilla marketing campaigns. Born out of urban creativity rather than the comfort of the corporate boardroom, the key element of any great marketing stunt is its ability to go wrong. Without this, it's not actually a stunt at all.

Talk radio station CFRB Toronto provides one of the best of the year so far. Keen to promote its reputation for hard talk, the network paid street prostitutes to hold signs reading "Should prostitution be legal?"

Considered contentious but clever, the tactic received a positive reception from Toronto residents. Yet only slight changes in the message and messenger tipped the scale of public opinion: While the issues around prostitution were deemed acceptable subject matter for the station's campaign, paying Toronto's street beggars to carry signs asking "should panhandling be legal?" were seen to exploit the homeless and belittle their plight.

Risky, contentious and always unpredictable, the CFRB radio campaign is guerrilla marketing at its best.  Admired by some, scorned by others and possibly misunderstood by everyone else, marketing people like us need to be bold enough to execute when those around us start to falter and nimble enough to turn unexpected results to our advantage when outcomes deviate from the plan.

For the steadfast and sure, the rewards can be priceless: In CFRB Talk Radio's case generating big time buzz required only basic budget. Billboard print runs of just dozens created props for photo-ops which subsequently spread like wildfire across the country online, on TV and in the press. When contentious issues resonated with this the target audience, the station's reputation for hardtalk enhanced. Crucially, when issues were deemed exploitative, the station's reputation for hardtalk may have been enhanced even more.

Even in our biggest corporates, "no or low cost" remains the guerrilla campaigners mantra. Way back in 2002 Vodafone famously commissioned a streaker to create some bare faced disruption at the Tri-Nations. Aired in newspapers and TV stations the word over, the paltry £30,000 allegedly paid out in fines and payoffs by Vodafone after the event is still ranked as one of the most cost effective global communications campaigns in the guerrilla marketers Hall of Fame.

Similarly, after a long series of pommie-bashing comments from former Wallabies legend David Campese during the 2003 Rugby World Cup, betting firm Ladbrokes scored high when they forced Australia's most capped player into a public showdown.

Forcing him to back up his claims that England was not good enough to win the tournament, Ladbrokes took a gamble and won. Campese eventually ended up having to do a walk of shame along the length of Oxford Street wearing a sandwich board proclaiming that the best team won. The stunt, which generated global media for the betting company, was well worth the expenditure: Campese asked only that a donation be made to London's Great Ormond Street Children's Hospital.

The good news is that more and more of us are working out how to inject the highly creative tactics associated with good guerrilla marketing into campaigns that remain firmly on the right side of the law. Perhaps dismissed by the hard-core adventurers as Guerrilla "lite", these tactics are "cheeky" yet legal. Offering safer havens to marketing experts creative enough to balance unprecedented ideas with corporate sanction, when we get this right, the result is high impact marketing that comes in at a fraction of the price of conventional ad spend.

Marketing Mavericks: our pick of the greatest guerrilla campaigns

From left to right (Hover over pictures to enlarge):

Carlsberg's best litter in the word campaign: Fake tenner's distributed randomly around UK pubs get punters talking about aforementioned beer.

Quiet please: it's you know who: During the ATP tournament, soft drinks business Schweppes carefully coordinates the appearance of its famous "Schhhhhh" tag line to appear on the scoreboard every time the umpire demands "quiet please".

Shaving Eggscellence: Creating high impact with minimal budget, Wilkinson's "Every man deserves smooth skin" promotion helps launch the company's new four blade razor in European supermarkets.

Listermint's This wont hurt a bit: Patients in eastern European dental surgeries are providing a captive audience for Listerine's guerrilla campaign. Ads for the mouthwash are placed directly above the chair.