The guest said soon after settling into the room, she overheard a conversation between the host husband and wife couple, where the woman alleged they were drug addicts.
The guest said she confronted the wife and offered her to check their bags, but she did not want to.
"Her only presumption is she has a home drug detector and it blinked. I told her that is very stupid as that is only presumptive and that she can't prove it," the guest said.
The guests left the house and spent the night in their car.
The guest, who is a health worker, said the incident had affected her mental health and planned to file a complaint against the woman through the Citizens Advice Bureau.
"Clearly it was simple racism where she tries to cover with a stupid rationale," she said.
The Herald has been unable to contact the hosts.