Absolutely wonderful aromas can be produced from cooking, however, so too can pungent & irritating odours. Not all smells are received by people in the same manner as different people have various tastes. You may be cooking large quantities of meat over a charcoal grill which will produce a lot of smoke & could affect local asthmatics. Most exhaust systems discharge the cooking fumes locally & any strong or ‘smelly’ odours will likely deter potential customers. In these notions you can see why controlling the odours that emanate from your cooking equipment is vital.