Making the best suggestions....
Thank you so very much for your follow up - Your service tech/field supervisor Jack F. was extremely helpful in making suggestions regarding this situation. Although he, like myself and my maintenance guy, did not detect any odor in the apartment (that is not to say there was not any foul odor, just that during the times we were there, we could not detect any odor). Jack suggested that by changing out the sink might be a good solution. Since this seems like the least expensive and yet most efficient and effective way to go as the next step - we shall do this.
Jack also suggested as a last resort, if changing the sink out did not rectify the situation, then we could contact your business again to possibly do a 'smoke bombing'. He did advise on the exact procedure and what we would have to do, should we follow through on this.
The service / advise that was provided to us, not only by Jack, but by the very quick response from emails and phone contact, puts your business of RAINFOREST at the top of my list for plumbing companies in Arizona.
Thank you, again, for your thoughtful and helpful service.