I'm currently looking at ways to prove my expertise and provide evidence of skills / experience to potential contract owners. 

Went to a reputable site or two - freelancer type site - and they use tests to check skills. Took said tests, and passed them all  - mostly in the top 20% - which is good. However I have also noted at least 20% of the questions are flawed, wrong or unanswerable. I've fed back to the question makers but dont seem to be getting through.

Here is one of my favourite examples:

6. Which of the following are important when dealing with a helpdesk customer over the telephone?

Answers:
A - Being good at listening.
B - Developing a rapport by matching the caller’s tone, tempo, and word usage.
C - Having a pleasant telephone voice.
D - “Placing” the caller’s complaint and “leading” them to a solution?
E - All of the above

I have two choices in answering this question - either choose one of A, B, C or D or chose E. I cant choose 2 of  A-D, only one.

 Hmm. Correct answer turns out to be E - all of the above. However it's wrong. Why?

 answer B says, "B - Developing a rapport by matching the caller’s tone, tempo, and word usage."

If I did "Developing a rapport by matching the caller’s tone, tempo, and word usage." with a highly angry client, who is using profanity, and screaming at me, there would not be a good rapport created when I screamed profanities down the phone back at them. (matching tone, tempo and word usage)

Good PC answers - that are wrong in the real world. 

Another question: SEO - what image types does Google index.

RAW

PNG

TIFF

and 2 other answers that dont get indexed.

Unfortunately Google does both TIFF and PNG. Cant answer both - so took a stab they thought PNG - despite it being wrong as Google indexes TIFF as well as PNG.

There must be some type of freelancer site - with decent testing and examination processes in place. Surely??!?