Rewards of up to £1m (€1.56m) have been put up by UK newspapers in an attempt to boost the search for missing schoolgirls Holly Wells and Jessica Chapman.
But these have received a lukewarm response from police who fear they could encourage time-wasters to provide false leads which would disrupt from the investigation.
A shop assistant in Soham told BBC Radio 4's Today programme that one couple admitted choosing the town for a country walk because there was a chance they might find the girls and claim the cash.
Speaking anonymously she said: "I had a couple from London that came to say they were going to have a walk in the country and they decided they would come an walk here and, perhaps - it sounds quite sick really - but perhaps they will find them and be able to claim the reward, which personally I think is absolutely terrible."