Avoid Weasel Words
Weasel words are words or statements that seemingly support statements without attributing opinions to verifiable sources. They give the force of authority to a phrase or a sentence without letting the reader decide whether the source of the opinion is reliable. If a statement can't stand without weasel words, it lacks neutral point of view; either a source for the statement should be found, or the statement should be removed. If a statement can stand without weasel words, they may be undermining its neutrality and the statement may be better off standing without them.
For example, "Vancouver, BC is the nicest city in the world," is a biased or normative statement. Application of a weasel word can give the illusion of neutral point of view: "Some people say Vancouver, BC is the nicest city in the world."
Although this is an improvement since it no longer states the opinion as fact, it remains uninformative:
In other words, you should avoid weasel words if you hope to write effectively. This is important because, as the Wikipedia article stipulates:
Weasel words do not really give a neutral point of view; they just spread hearsay, or couch personal opinion in vague, indirect syntax. It is better to put a name and a face on an opinion than to assign an opinion to an anonymous source.
Not only is this good practice for contributing to Wikipedia, but it's a good practice for good writing. If you want to know more and read some examples of weasel words, check out the Wikipedia article.