When people define who they want for a long term relationship, they are often seeking someone who simply does not exist in the real world. They want a person who is at the high end of every measurable attribute, but people tend to be balanced. A person who is incredibly intelligent may not be good looking, or their ability to express emotions may be limited. A fun person might be highly intelligent, but they might run roughshod over others.
Physical attractiveness is the most often mentioned attribute, but not all people will look their best on any given day. A person who has just worked a double shift might look sloppy and unkempt, but they might generally look better when they have had some needed rest. Dating a real person means knowing that people will not always be at their best on any given day, and being able to understand this gives a dater a better chance of finding a good match.