I looked at two houses in Irving today, and the two could not have been different. One, was a great house that the sellers were impossible to build rapport with. The other, was a house that needed 30K+ in work, and the seller was a nice guy. The seller and I got along amazingly well.
The point behind this, is the next buyer might have found the two to be the complete opposite of what I did. Depending on their personality, mood, or conflicts that morning, or on the way to the house.
Always try to understand you only have control of your own attitude and mood, and not the seller's. Just do your best, and be nice!