The problem with shops is, so often, the help, who, I guess, are forced to speak to you, and forced to recommend whatever the latest crap product is. This is why I really like shops where the staff leave you alone.
Sephora is very good this way, even if their selection, though broad, is a bit shallow. And the CdG boutique is lovely too: all the fragrances on a rack, with no sales people in sight. It's perfect.
Tabac Blond is on my to-try list. Is there a Caron boutique in London?