Bad days happen, and sometimes those of us who don't always reply (or even decline) get to reap that bitter harvest.
For a recent example, I offered a 500 count R for a much higher count R, the trade would have completed both our sets.
The card I was (and still am) looking for is a Dodge Club blue, in case anyone is wondering...)
I don't take any of it personally. I'm super busy, and probably many other people are also super busy, and sometimes it's just easier to decline everything which isn't a slam dunk, rather than spend the time to figure out whether the trade solves a problem.
On a related note, I've been on NM about 3 years now, and have learned that 1. I'm not going to be able to collect everything, or even most things now (not even Eric can do that now), and 2. patience pays off in a big way. Once in a while something I really want falls into my lap.