There is a horrible smell in the kitchen sink at my buddies house. We have poured boiled water, vinegar, febreze, and alcohol down it. What can we use to fix the problem.
I would remove the trap and see if something stuck there is causing the problem. Bleach will normally kill any bacteria causing a smell, but if something is remaining in the trap, the smell could continue.
I have used ice cubes and Tang (powdered citrus drink) in order to clean smelly garbage disposals. If that does not work, I would start digging around for other possible problems. Is the "P" trap functioning properly to prevent gasses from escaping? is there a dishwasher attached to the same line? If so, run hot water and Tang for a complete cycle and see if this helps at all.