"If they make out they are 7ft tall and built like Sonny Bill Williams when actually they might be someone who looks like Danny DeVito."
Mr Dingwall said he was approached because people, mainly women, wanted peace of mind.
"Some people are on there for legitimate reasons and others are on there for personal gain. A lot of people just want me to confirm that he is as good as he looks so they don't get taken for a ride. Relationships are important to everyone."
He said internet dating was great for some people, especially middle-aged people who were beyond the pub scene.
Mr Dingwall's new clientele mirrors the trend in Australia where thousands are enlisting private investigators to do background checks on potential partners they meet online.
Julia Robson, from DateScreen, which specialises in investigating online Romeos, said she received about 20 calls a day to the service she launched in June.
Lachlan Jarvis, from Lyonswood Investigations and Forensic Group, said investigating cyber love rats now made up about 10 per cent of the group's investigations business.
The inquiries come from men and women wanting to check would-be lovers are not already married or lying about their wealth or aren't crooks with criminal records.
The Australian Competition and Consumer Commission said Australians were scammed of more than $21 million while trying to find love online last year.
Meanwhile, New Zealand's single Kiwis have been in an online dating frenzy. FindSomeone manager Rick Davies said the online dating website founded in 2001 was experiencing its highest ever level of activity this week.
He said people aged between 18 and 35 were driving online dating activity to record levels.
