the length of asking someone to write a fake review. >> makes it easier for people to find you. >> reporter: the owner's plan backfired. >> busted in the sting. yelp police. >> reporter: by some estimates, 30% of online reviews are fakes from hotels to toys to books. so how do you spot them? here are the clues. truthful reviews often talk about physical space, using specific details like floor and small. fake reviewers often talk about themselves and their companions. words like "husband" can be red flags. as for joe garvey -- >> reporter: do you feel it was dishonest in any way? >> yeah, it was a little bit. >> reporter: was it worth doing? >> no, no. >> cecilia vega, abc news, san francisco. >> the interweb is a messy place. yelp is incredibly popular. i love it. and by the end of the second quarter of this year, they have more than 30 million reviews agnel p.