The princess was wearing garish makeup.

Literal

Princess [subject-が] garish makeup [object-を] was-doing.

あくどい ('gaudy, garish, over-the-top') is a vivid adjective for excessive or tasteless styling. It can also mean 'unscrupulous' in other contexts, but here it's purely visual. 化粧をしていた uses ~ていた for an ongoing state in the past.