Horns: Why don't they image well?

Anytime you use a giant waveguide to spread high frequencies you are trading off a large soundstage (flat power response) with less precise imaging (since the highs are getting stretched over a wider area).

As I mentioned earlier there is a new Klipsch La Scala.  It is the model AL5.

Partly correct, but for many years horn systems have included "phase plugs" or their equivalent to keep horns from "beaming" high frequencies. The high end horn systems I use for pro sound are designed to spread high frequencies over a large area, and they do that well, and the Klipsch Heresy IIIs I use in my home system easily have as good or better dispersion of high frequencies than the dynamic speakers I've owned over the years. 

Watch this folks....

I came to this thread really opposed to horns, and I'm not 100% on them today, but I'm not going to let the misinformation go unchallenged.

Horns don't "spread the sound". They mechanically couple a pressure impulse to the environment. Horns are MORE directional than dynamic drivers with more controlled dispersion. 

Indeed they are "MORE directional than ..," and It should make them less fuzzy about room acoustics, not to say they don't benefit from absolute care with regard to placement and even very minute changes in their positioning and toe-in, but that's true for a variety of speakers regardless of principle. Quite a few horn speakers can be placed in close proximity to the rear wall, with many of them even requiring it, and this alleviates to an extend their typical large size and intrusion in a living-/listening room milieu, without affecting "sound staging" negatively. 

Personally I fancy horn speakers often being rather wide (as opposed to the narrow baffle/deep enclosure seen with most direct radiating speakers), as it seems to subjectively highlight this big, vibrant "wall of sound"-like sonic presentation. If they're made with real-wood veneering or even hardwood they are also lovely to look at with their broad front panels and horns. I miss the sensation of speakers as wood furniture that actually looks and feels (and even smells) like real wood (instead of the lacquer-infested and glossy appearance from most modern speakers), while unapologetically taking up space as big sculptures in one's home environment, but that's just me.  

My own listening room is quite "alive" btw, an acoustic environment that's most pleasing for me to actually occupy, and with the all-horn speakers I use it's a non-issue sonically. Generally though I prefer diffusion over too much absorbing with any speakers, so not to rob the sound of what I regard as a natural life. But, I digress..