Section 50. At the time and place designated in the notice, the person complained against, or any person claiming an interest in the alcoholic beverages and vessel seized, or any part thereof, may appear and make his claim verbally or in writing, and a record of his appearance and claim shall be made, and he shall be admitted as a party to the trial. Whether a claim as aforesaid is made or not, the court shall proceed to try, hear and determine the allegations of such complaint, and whether said beverages and vessels, or any part thereof, are forfeited. If it appears that the beverages, or any part thereof, were at the time of making the complaint owned or kept by the person alleged therein for the purpose of being sold in violation of law, the court shall render judgment that such and so much of the beverages so seized as were so unlawfully kept, and the vessels in which they are contained, shall, except as hereinafter provided, be forfeited to the commonwealth. If a motor vehicle is seized under the provisions of this chapter and is held to be a container or implement of sale of alcoholic beverages contrary to law, the court shall, unless good cause to the contrary is shown, order a sale of such motor vehicle by public auction and the officer making the sale, after deducting the expense of keeping the motor vehicle, the fee for the seizure and the cost of the sale, shall pay all liens, according to their priorities, which are established, by intervention or otherwise, at said trial or in other proceedings brought for said purpose, as being bona fide and as having been created without the lienor having any notice that such motor vehicle was being used or was to be used as a container or implement of sale of alcoholic beverages contrary to law. The balance, if any, of the proceeds of the sale shall be forfeited to the commonwealth and shall be paid by said officer into its treasury. All liens against any motor vehicle sold under the provisions of this section shall be transferred from said motor vehicle to the proceeds of its sale.