What don't vampires like?
Like humans, vampires are individuals with individual tastes and preferences. Unlike some of their fellow undead (zombies, for example), vampires don't lose their human consciousness when they transform. Like anyone else, their tastes will change over time, but certain likes and dislikes from their human life will carry over into their "new life".
That said, there are certain substances that all vampires are naturally repelled by. These naturally occurring substances contain chemical or mineral compounds that essentially act as irritants in the same way that humans have negative reactions to chemicals like Urushiol, found in poison ivy or Capsaicin, found in hot peppers. While direct contact with large amounts of these types of chemical irritants may cause serious injury, small amounts, or even just the smell of them can be enough to keep unwanted visitors at a distance.
Of course, there are the obvious elements that are deadly to vampires, such as silver, fire, and sunlight. These are not so much repellents as they are dangerous to them. That's kind of like saying that guns and knives are human repellents. Not really true, unless you suspect that someone might be using them against you. The true "repellents" are usually naturally occurring chemicals that vampires dislike to a significant degree - significant enough that often the smell alone will have them seeking a new target.
The most famous vampire repellent is garlic, and for good reason. Not only does the smell of garlic irritate vampires, but garlic is also a natural opponent of bacteria, one of which is a critical substance in vampire blood.
Interestingly, all of the substances that irritate vampires are the very same ones that irritate other blood-sucking creatures, such as mosquitoes. Though the species are not in any way related, there appears to be a very strong connection in that they all seem to be irritated and/or repelled by the same chemicals.
What are these chemicals, you may ask? There are many common plants that have these chemicals in them. Rosemary, peppermint, clove, and cinnamon are all effective bloodsucker repellents. To a slightly lesser extent cedar, geranium, pine, lavender, basil, and thyme also seem to be effective. One of the most effective repellents is anything "lemon" - including some plants related more by name than by genetics. Of course lemons themselves are effective, but also lemon eucalyptus, lemongrass, and citronella are powerful enough that the scent alone repels even the mightiest of bloodsuckers.
It is commonly believed that these substances are most effective when crushed up and made into a sort of "perfume" by mixing them with an oil base (rather than a water base).