There is a list of words The Whissel Dictionary ignores. You can view the list here. You can edit it in notepad.
Some texts can have a large number of words that add to the affective content, without adding meaning. Words like 'a', 'the', 'an', and others can make a text seem to have more meaning than it really does.
There are words that do not appear when using texts translated from other languages.
For example, "I go" is two words in English, but only one word ("Voy") in Spanish. If you are comparing analyses of two different texts, and one is in English and the other is in Spanish, you might consider adding the word "I" to the list of ignored words, so that the word "I" doesn't affect your comparisons.
It's important that you understand the grammar of both languages when comparing texts in English to those translated from other languages.
Before adding a word to the kill list:
1) make sure the word is in the Whissell Dictionary.
2) Make sure the word's scores are close to the mean.
A simple way to check is to type the word into the the text field, and then analyze it by itself.