Is the fee you pay for a marketing agency worth it?

It seems to me that there are a large number of marketing agencies out there ripping business owners off.

Some examples:
• Charging more money than they actually help you invest in ads
• Not accurately reporting on ROAS
• Blaming you or another team/company for their poor results
• Not being transparent otherwise keeping you in the dark about the results you are paying for

I would love to hear your opinions on this.

from Is the fee you pay for a marketing agency worth it?