I don't know about an "ashtray" tasting flavor but I can recommend one that is the closest to a cigarette flavor that I found. Seedman's Commercial Cigarette has a straight up cigarette tobacco taste with NO perfume undertones. A little dab of this mixed with some TA (diluted with EM and PG) might be what you're looking for. It was too ciggie tasting for me after being off of the smokes for over a year but I could see where it might be perfect for someone trying to replicate that type of flavor. It is a very STRONG flavor so start LOW and work up. I found it much too strong at 1% but of course we all know how subjective the taste factor is. Good luck! Here's a link Tobacco Flavorings for Home Grown Tobacco to Seedman flavors.