The source of foul smells and odours in the house or place of work is most often difficult to trace.
Odour detection is key. Covering up or masking odours means the smell is probably going to come back.
Most odour problems we find are due to dead animals, birds, and vermin such as rats, mice and squirrels, that have died in void spaces. Vermin and birds can die a long way from what seems to be the source of the worst.