Kind of a sensitive subject so I will try and be a bit vague, but has anyone had to report an examiner before, and if so, how?

In the area that I'm in, there are several large flight schools, 2 with a high asian student population. I understand that there is going to be a higher fail rate with the foreign students because there might be issues with their English proficiency. However, there has been an exceptionally high fail rate, with many getting failed twice. Also, one of the examiners used a racial slur during the test.

Another examiner was essentially asked to leave from the school (or rather not asked back) as he failed 10 of the asian students in a row. I'm asking on behalf of a friend (really) who is doing his Part 61, independently, and had the misfortune of testing with said examiner. The examiner has now failed him twice, which he and his instructor believe to be unfair. He's worried that this will affect his future employment.

I was just wondering if there is any recourse, especially with the examiner that used a racial slur during a student's test. (Unfortunately, there is no hard evidence, but there are a large number of students that have had the same experience).

Any advice would be much appreciated.

Yes, feel free to complain about said examiner.
Some of those guys think they are Gods in their own Kingdoms.
Overall I have had very little problems with examiners, busted once, but my own fault..
If an examiner keep failing folks again and again, there is a big problem, either with the training department, or with the examiner..

I have been a check airman on various planes and had a touch of the God-blessing myself, but recommend more training if there was a problem, or refused to sign guys off, not sure I ever failed somebody.
A bit different with a designee or an FAA type examiner, yet their job is to do fair check rides, not to lubricate their own egos by busting foreign pilots left and right..

There are absolutely problems with certain examiners. But on the other hand when you were hearing a story like this you're only hearing one side of the story and never why the examiner failed anyone. If any DPE is failing 10 students in a row the FAA is going to be looking at the DPE and his plan of action. The FAA will most likely be looking at any flight school that has 10 students fail in a row also - Asian or not. The complaint could be made to the local FSDO who has oversight on the DPEs.

If it is a foreign language issue, the examiner is required to determine ICAO level 4 proficiency. They often do this during the oral portion by having them read and comprehend a technical portion of the FARs or AIM. The practical test is discontinued at this point if they cannot prove ICAO level 4. I have met some foreign students that did not have this standard. Some schools have some remedial English classes for this reason.

If it is a racial issue, report it to the controlling FSDO, immediately.

There's no downside to refusing to fly with a particular examiner. Find another one. If the school pitches a fit, report both them and the examiner.

Researching your examiner is an important part of any checkride. Don't EVER take a checkride that you think you might fail for any reason. You can always fly the ride another day, but you can't ever erase a failed check.

Why don't you ask the instructor to sit in during the oral portion?
When I took my private many years ago, my instructor came along and sat in the corner, taking notes.