If you want to make your writing clearer and more interesting, use be verbs sparingly.
The verb to be includes:
Be, being, been, am, is, are, was were.
Be verbs make text dull partly because of overuse, but also because they remove the reader one step from the action. They take readers the long route to meaning and can be long-winded.
- Fred is dismissive of cowboy films
- Fred dismisses cowboy films.
The second phrase has more energy, it propels the reader along. It expresses the same idea in a clearer, more concise way.
Be verbs turn up in passive language, staying away from them helps keep your writing in the active voice.
Old-school newspapers taught journalists to never use be verbs in headlines, but prefer strong action verbs instead.