I have been paying attention to aircraft spotting since I posted this topic. I fly real airplanes five days a week.
I noticed that spotting an airplane, regardless size (except for white or aluminum skins and on a crisp clear day) is nearly imposable below the horizon beyond one mile initialy. Spotting one closer and tracking it beyond one mile even out to about three miles is not hard to do. Most dark camo (I fly in an MOA daily) or even gray aircraft are easier to spot when moving at 300kts than are the slower helis. Even a damn C-141 at 500 agl can scare the toejam outta me.
Above the horizon, the opposit applys. Its harder to see lighter colored aircraft. Darker colored aircraft on an average ten mile visabilty day can be spotted at about five miles. Larger aircarft obviously can be spotted further away pending visabilty.
On hazy days, looking up at an airliner, its easy to see because of the reflection from the haze layer or clouds. On cristal clear days with no vaper trails, they are harder to spot. Same goes for most aircraft flying high. Even trying to spot a small twin at 10k is hard when the visability is reduced due to haze.
In AH I just get tired of chasing "dots" that end up being so damn far away.