Say I have a long option that is 0.01 bid / 0.02 ask. I'm fine taking the bid for it. There's no way it will expire ITM today and the only use it has would be to free up margin for someone else. So if I can get 0.0001 / sh for it, I'd take it. However, with IB SMART tiered commission structure, if I sold at the bid, there's a good chance I could pay more in commissions than the $1 that I would receive in total from the sale. I know it's not much, but I usually end up with a lot of these worthless options at expiration and I could easily write an algorithm to sell them at expiration if it is possible to do for any kind of net credit taking into account commissions.