What some people I know do is they check the bid price and lowest offer at peakmonsters and then they put a price that is lower than the offer price. But if the bid price is fair, the put the bid price so that the card sells fast.

In both scenario, it is the buyer that determine whether they want to pay using Steem or DEC.

I've never tried dumping a card with the DEC conversion because the cards are converted at a way too cheap rate.