Interesting question Tom.
I definitely notice signature scents or any scent for that matter, good or bad. Two in particular that stick in my mind for the right reasons would be the Sofitel at Heathrow T5 and the Hilton Syon Park London Hotel. Their scents subconsciously make one feel welcome and provide that all important positive first impression.
I would guess it’s a marketing strategy that most firms are catching on to. Supermarket chains have been doing this for years by pumping the store entrances with the aromas that come from their bakeries, and why not!? – Studies have proved over and over that exciting the senses of consumers is likely to have a direct correlation with increased sales and profits.