For sure some examiners do discriminate especially in the speaking test where you are setting face to face to the examiner and he can see how do you look and where you are from, in addition to this, the examiner knows that you are applying for immigration since you are doing the general training test and that you need to get 7 in speaking to get the maximum points (it gives you 50 points in the express entry system) so he can easily prevent you from getting this score.
More importantly, IELTS is the most non-transparent exam ever, no one can verify the marking system, and if they do mistakes you are not allowed to check them even when you request rescoring, moreover they try to make rescoring impossible with a fee of 160 dollars and a waiting period of 8 weeks while the exam itself was marked in 10 days !