I've read the previous posts and all of those things I've tried. Lemon, bleach, boiling water, baking soda and vinegar, drano. I have taken apart all visible pipes from under the sink cleaned them and put them back including the disposal. There were no clogs, and my sink still drains well. I do have a dishwasher but this smell started before we installed the dishwasher. However it seems to make it worse running it. It is a condo on the second level so I have some concerns about ripping out the dry wall not sure how far I will even be able to see and don't want to run into a problem that may effect my neighbors below if possible. The smell could be contained at one point by just capping the sink with it's plug, but with the warmer temperatures that no longer works and it is so bad you can smell it in other rooms of the house including my upstairs open loft. I have to think it may be sewer gas because it is stronger certain times of day and comes in waves. I try not to gag as I write this, and there's no way I could ever have company! Please if you have any suggestions do tell.

Most likely, smell is caused by bacteria in your drain pipes and / or rotting food in your dishwasher drain system. You have to kill the bacteria to get rid of it. To do so, you can use combination of Vinegar and Baking Soda or buy household Bleach and pour it into drains. Air-gap and discharge hose from Dishwasher are hard to clean and I would replace them all with new material. Air Gap is inexpensive and easily replaceable so is 5/8" and 7/8" hose that connects Dishwasher and sink. . Also, make sure your dishwasher is clean at pump intake ( inside / bottom / under filter cover ). Run several cycles with clean water and mixture of bleach and detergent. Don't use dishwasher for few days while you are in process of cleaning it. The smell won't go away in one cycle but the smell will slowly dissipate over period of few days. Advice: do not put food into garbage disposer. Empty plates into plastic bag. Same applies to dishwasher: pre-clean all dishes before you insert them into dishwasher. Let me know how it went. Back to you. Milo