Barrel distortion can be corrected with Lightroom 3, Photoshop or other photo editing software but the only way to get rid of perspective distortion is to zoom your ultra wide lens to a longer focal length. How do you tell if a image has perspective distortion? If it looks strange, that's how. Many would say that perspective distortion is a matter of personal taste. I submit that we only notice perspective distortion when the focal length of the lens is significantly different that the focal length of the human eye. What's the focal length of the human eye? If you google this, you'll find that there are a number of answers. I believe the correct answer is between 22 and 24mm. Here's why:
My conclusion it's not an accident that visually sophisticated preferences gravitate to around 24mm, because that's very close to what the human system is use to.
I know, real estate marketing images shot with a lens with an effective focal length less than 24mm are very common. Images shot at 14mm and 16mm are used all the time Super wide has almost become a "real estate marketing" look. But in my experience, the farther you get below about 22mm effective, the more likely it is you will get negative feedback from clients and viewers. Some will not notice or care but many will. I had one home seller call my 16mm images of his home "cartoon like". It took me a while to even figure out what he was talking about but it was the perspective distortion. Another common criticism you hear is that agents are trying to "make rooms look bigger than they really are". Many home buyers feel scammed when you use super wide shots. I'm not saying always shoot at 24mm, I'm saying be aware of the fact that not everyone thinks ultra wide shots are cool.
I'm going to even go a step further. Most visual distractions in marketing photographs are created when images contain visual effects that are radically different than what the human visual system is used to. For example:
All of these visual effects in interior images distract from the strength of an image because they make images unusual and unbelievable to the human eye/brain. The more visual distractions, the harder it is for the viewer to focus on the real purpose of the photo. Removing all these image problems will make the image will be stronger and more effective.