The online bidding platforms are attractive. As a buyer, they allow you to peruse hundreds of cars without leaving your home. You can ask questions and request more pictures or videos. You can benefit from the questions and observations of others, some who might even know what they are talking about!
As a seller, you can set a reserve (recommended), don't have to travel to an auction site and usually pay less in the way of premiums and fees. However as a seller, you're on the hook for comprehensive photography including documentation, have to endure lots of questions and little real payment guarantees.
As a buyer, you likely have not actually seen or driven the vehicle, so you may end up being disappointed (Yes, I have been there). So in the end, weigh the risks and proceed with caution.
You can mitigate your risks. Do your research and consider hiring a local appraiser to check into your prospective purchase/sale and provide some professional advice. It’s usually money well spent.