There was a somewhat famous case involving a certain Yacht yard and a couple out on the west coast
involving tax implications of trying to write off a portion of the boat's cost against a supposed 'business' where the owners took their boat to various shows etc. to represent the yard for a small percentage of the profit gained on any ultimate purchase
of a boat from the yard by someone that had been on their boat...there , does that make sense?
Didn't to the Tax Court either who ended up disallowing the deductions and imposing the tax
OTOH I could see where a new boat purchaser might be cut a special deal by the builder
for agreeing to let the boat be seen at a number of shows..maybe some extras as *freebies* etc., but no first hand experience of that, (tho I have heard a few stories..)