Loaded questiom ! I think there is more to this question than meets the eye.
#1 - Logging in factor: I log in daily, I might have work to do onsite. Doesn't mean I'm always on to trade.
#2 - Inventory: Huge Factor! Are we talking about a trade with a trader with 4,000 cards or 4,000,000 cards? This alone could be a deal breaker. Also, how organized is the trader? Another deal breaker...looking for 1 card in a mess of billions. The truth however is, I probably have the card[s], just can't locate them ...like bingo!
#3 - COMMUNICATION should be 1st and foremost. BOTH traders.
With that said, WD from an offer used to rankle me, especially when I didn't even look at it yet, let alone respond to it. Since I generally don't make offers but receive plenty. I'm not sure how long, but I would have a sliding scale based on the above 3 factors. In today's world setting a hard and fast time frame doesn't work for me, but communicating is a must and may alleviate ill- will.
While on the subject of WDing, Declinig should also be considered. I hate TO DECLINE a well formatted offer, the trader obviously had to work hard to put the offer together and I decline lickety-split. Once again the 3 factors come into play, and should be considered. I do reply to all offers in time, some offers I can get out asap, others are "multi-everything" that are complex and take time. In offers of a 100 card mixed offer, my timeline can take a while, so unfortunately these traders need the patience of a saint.
So wrapping up, my intentions are honorable but sometimes complicated. I would never be deceitful or try to "fake news" my traders. I don't get upset with WD offers anymore [although I always wonder why??], sometimes things in life get in the way of a "cardboard trade". To this day I rarely decline an offer, could be irritating to my trader, but I always explain my reasoning.
My Soapbox, My way, My 2-cents...........~bob~