I find that wierd, I just booked accommodation and most of the places either said:
This trip is non-refundable (and you had to pay in full first)
OR
This trip is cancellable (nothing to pay now and you can cancel up to approx 2 weeks before)
So if you pay now, what is the refund policy?
For the non-refundable trips, the rates were cheaper by 10-20% by the way. What did it say about payment when you booked?
So I wonder if they advertised it at the higher cancellable rate, but are now asking you for payment in full?
How does the price compare with apartments where you can cancel?
Be aware that if you do pay, the trip may become non-cancellable, any cancellation refund would have to be covered under (if you buy some) insurance.
So it's not so much whether they are genuine, this should all be sorted at the time of booking.