I am no expert on the causes of yellow spunk but apparently there are a few.
It may be due to infections, STDs, or retention of urine because of infections. More commonly it is due to dehydration, use of medicines, diet, old age or/and retention of sperm for extended periods (not ejaculating often enough)!
If I had a choice, I would go with white spunk like Adele. Between clear and yellow I'd go with clear. Yellow looks a bit sickly in comparison though I never had any problems with it. If you see red, it is danger, run!!!