The more popular the phrase, the lower the conversion
rate. Many advertisers focus only on the broad one or two-word
key phrases that get the highest search volume. When you're paying
per click, this can cost you severely.
An Example...
Let's say someone searches for the word "hotel." Their
goal is to book a hotel reservation online in a specific city
and they know which hotel chain they want to use. When this person
looks at the results for the word "hotel," he/she will
realize that the results are not specific enough and, therefore,
are not relevant. They might click on a few links and cost you
money before they realize this however