But an unusual auction sale later this month reveals that spy cameras, at least, have been around for more than a century and come in an extraordinary variety of secret guises.
The examples to go on sale at Christie's, South Kensington, in west London, were gathered by an anonymous French collector, whose quirk was to find as many examples as possible, dating from the Victorians, of the trend for concealed cameras.
These were designed for both men and women - erring husbands may well have been at the wrong end of their concealed lenses - and now command prices up to tens of thousands of pounds.
A popular type was the camera gun. Many of these models, which started in the 1850s, were unconvincing in terms of disguise - Christie's is selling an Erac gun camera consisting merely of a grip without the barrel - but they did have the advantage of reducing blurring.
One of the better varieties is included in the sale on 17 January: the Japanese Toko Kogaku, which offers a sight and dummy magazine and is estimated at pounds 400 to pounds 600. If a gun seems a little crude, aspiring spies should consider the watch camera. Christie's is offering the Steineck ABC made in 1948 by Dr R Steiner, a prolific German inventor who was a notoriously bad businessman when it came to marketing his designs.
His Steineck ABC - estimated at up to pounds 1,200 with its original box - is considered one of the best of its kind although only the unobservant would have been fooled. A small lens pokes out where the XII should be, while a button at six o' clock activates the camera.
Women might prefer the photo-vanity set from Ansco Photo Products of Binghampton, New York. Estimated at up to pounds 1,400, this black vanity case is fitted with a hidden camera, comb, mirror and make-up set. It takes snaps through a small opening under the carry-strap.
Other gadgets include the notebook camera complete with pen (up to pounds 140), the cigarette box camera (four "brands" including Marlboro; up to pounds 140), or the lighter camera, with its Zippo-style case (up to pounds 150).
Last but not least is Bloch's remarkably unconvincing 1890 photo-cravat camera, the size of a spectacle case. Designed to fit inside a cravat with its lens poking from the position usually taken by the pin, this will command the highest price of all, likely to be as much as pounds 18,000.