My new to AirBNB guests seem to find this really 'suspicious' but what typically happens is
a) someone sends an enquiry set for one person....then go to book and it's more than one person (and I have an additional guest fee)
b) they don't realise that AirBNB is charging them a fee on top of the room rate and any cleaning fee etc (so even if they are booking for one person, one night, the number isn't going to be the advertised rate)
c) they did a search without dates in which case my 'base rate' is the rate shown in the listings for my area...but the dates they want to book are on a diferent rate (ie, they search 'Shepherds Bush' and see me at X, but they plan to come in July when the rate is higher)
For me it's usually one of these things....