Wow! I-pet, you have really good use of English. Will you be my Mistress?
It is a common misconception that subs are not as well educated, cultured or capable as Dominants. There is a perception that the sub has a need to be 'looked after' and therefore is less capable.
This is, of course, as any on here will tell you, total bollocks. However, misconceptions have a nasty tendency to persist regardless of the evidence. Most Dominants enjoy having a sub/slave who is articulate, intelligent and capable. What is the use of a useless slave? They need to earn money to keep you in the state to which you are acustomed, they need to be able to manage your household so you don't have to, they need to perform quite complex tasks for you and it is no good if you have to stand over them telling them what to do and how to do it all the time. Therefore, while intelligence may not be a primary focus of their search (or even an overt focus) you can bet it makes a difference when deciding between two otherwise similar subs.
I suppose the 'stupid' perception comes from not being able to do anything unless ordered to do so - lacking independence therefore demonstrating a lack of independent thought therefore being unintelligent. I think this is a misperception based on not really understanding the difference between 'not doing something because they are too stupid to think of doing it' and 'not doing something because my Dom will punish me if I do something without explicit permission'.
I have found that the majority of posters on this forum are highly intelligent and articulate people. I have a suspicion (and would love to do the research to find out for certain) that the scene attracts those with a higher than average intelligence - those who are in general more likely to be willing to explore beyond the fringes of vanilla sex - and that the Dom/sub intelligence levels are about equal on average.