The following works for me when disabling Findbugs in a child POM:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>findbugs-maven-plugin</artifactId>
<executions>
<execution>
<id>ID_AS_IN_PARENT</id> <!-- id is necessary sometimes -->
<phase>none</phase>
</execution>
</executions>
</plugin>
Note: the full definition of the Findbugs plugin is in our parent/super POM, so it'll inherit the version and so-on.
In Maven 3, you'll need to use:
<configuration>
<skip>true</skip>
</configuration>
for the plugin.