It has been estimated that as many as 75% of all orchids are fragrant, or give off scent, which in some instances are extremely repulsive smells. Flowers release scents that give them the best chance of attracting the right pollinators, so even the times that the fragrances are produced is during the time when the pollinator of that species would be active. This is because fragrance production consumes energy. Therefore the timing of scent production often coincides with the time of visitation of pollinators to use the least energy to achieve the maximum effect.
Here are some examples of this:
Clowesia rosea smells of Vicks Vapo rub in the morning and cinnamon in the afternoon.
Catasetum expansum smells of turpentine in the morning and rye bread in the afternoon.
Epidendrum falcatum, has a delicate, haunting scent of jasmine in the morning that turns to a stronger note resembling that of Easter lilies or narcissi during the afternoon.
Encyclia fragrans smells of honey and vanilla in the mornings.
Other fragrant orchids include:
Maxillaria tenuifolia smells overpoweringly like coconut and tropical suntan lotion.
Stanhopeas have an interesting chocolate-peppermint fragrance that lasts one to three days.
Lycaste locusta has the coloring and scent of a granny-smith apple.
Thunia marshalliana has an orange fragrance.
Masdevallia glandulosa smells deliciously of sweet cloves.
Zygopetalum intermedium has a rosy/lilac fragrance.
Calauthron bicornutum produce an unusual scent resembling a mixture of fruit and candies.
Cycnoches chlorochilon produces a penetrating jasmine fragrance.
Dendrobium anosmum perfumes the air with a scent of raspberries.
A few fragrant Phalaenopsis are Phal. Violacea and Phalaenopsis bellina. Both species have a sweet rosy-floral fragrance, but Phal. violacea has an additional blend of cinnamon.