Yes, its not a nice thought, but when I was rehoming my goats, I had some phone calls from, lets say, people who did not sound like they were offering the sort of home I wanted. One man rang, he had no holding number, but said he kept goats?, and they were going to a good home. I suspected they were for meat. Next day, a lady rang, saying she had a holding number, but from the same phone number, and I could hear the man in the background telling her what to say.
Its very hard to suss out some people. But quite often if you suggest either visiting beforehand, or bringing the goats, thats enough to put off some of the less genuine people. Or ask for their postcode, and go on a secret visit to see what sort of place it is.