The word "nigger" is derogatory any way you 'slice' it. To say 'I saw a nigger', means you saw a black person, but you are referring to that black person you saw in a derogatory sense.  You need not add 'stupid' to make it derogatory.  ..since a 'nigger', to people who use it, and HEAR it, already is 'suggesting' that the black being referred to is ALREADY stupid (& all the OTHER derogatory characteristics that are implied when using the word, to include lazy, poor hygiene, etc., is why he (or she) was being referred to as a 'nigger'.  So let's not 'sugar-coat' it.