I have almost no sense of smell, yet over the years I've had such a strong horrible smell from a few people that it almost made me sick. No one else could smell it and they had good sense of smell. Within a few months it was determined that those people all had cancer. Your comment about the gas leak triggered a memory as well. Once I could smell gas clear across the house from a closed garage. I called the gas company the next morning and they indicated I couldn't possibly have smelled it but sent someone to check it out. They couldn't find anything until they were about ready to leave and discovered a very small leak near the hot water heater. They still maintained that there was no way I could have smelled it.

Now I can hardly get near my 88 year old husband as the smell is so bad! He has Stage 3 Kidney (CKD), which can smell like urine but normally only in later stages. Nobody else in the family notices it. Even as a kid I couldn't pick up on odors - unless it was a skunk and I would comment on that but it never smelt as bad to me as to everyone else!