Answer:
Sudden change in your life.
Usually people will only notice a sudden negative change in their lives. For example, every time I run into a certain person on the street the following few weeks will be filled with bad luck for me. I would just pass it off as a normal fluctuation in my luck, health, relationships, etc. It took me years to realize that seeing "Liz" and having bad luck follow our meeting was linked. Her sister finally revealed to me that "Liz" is a black magic practitioner and enjoys passing bad luck onto all her female competition (she tried to seduce my husband once upon a time and still holds a grudge that I caught her). Now that I know, I simply cast a counter curse and protection spell upon myself and my home every few months to keep things smooth (not abundantly luck but not unlucky either, just normal).
However, spells can also bring you luck. For example, if you suddenly see an abundance of luck enter your life, it could be the result of someone casting a spell of luck, good fortune, health, wealth, etc. upon you. I've received requests from clients to cast a spell on a friend or family member of theirs to help them trough a rough patch. Though I don't like casting spells on unknowing "targets" as long as the spell is of positive energies, I don't really object (though I do prefer that they ask the person's permission before I cast).
An Alternate Thought
Much as the idea of there being people out there (witches or other) who randomly and secretly cast spells on others has a fascination for many people, the truth is there really are not that many who: A) can, B) would.
Most ethical practitioners who regularly cast spells do so only with the express permission and full knowledge of the person. Hence, if you asked for a spell, you would know it had been cast.
If you have engaged someone to cast for you, the effects are usually quite subtle, more of an appearance of things going "a bit more to your liking." This depends on the type of spell cast of course, but magic rarely if ever comes like a "bolt out of the blue."
- A prosperity spell does not generally result in an instant lottery win, but more often manifests as a great new job offering.
- A love spell will not have Brad Pitt or your favourite sports figure walk up to your door with flowers in his hand, but may manifest as a new person in your circle of acquaintances who shares your interests and is looking for a new friend.
- A protection spell may not "blast" a burglar who is about to break into your house, but instead send a police cruiser down your block, discouraging the thief from hanging around your neighbourhood.
If you are suddenly experiencing a "run of bad luck" I would suggest that the cause is more likely internal than external.
There is such a thing as cause and effect. If your thoughts and actions tend toward the negative, you are more likely to attract negative energies.
Should you find yourself in such a situation, stop and reflect, be willing to take responsibility for your own thoughts and actions and make an adjustment in your outlook.
Do a few "good deeds," be a bit more charitable (in words and actions) to others, look less to lay blame and more to changing the way things are.
It shouldn't take long before your "luck" will change, good things (that you may not have noticed before because of negativity) will become more evident.
Magic (the real magic, not the "movie magic") is available to everyone, it is in you as well as me and if you channel the positive and let go of the negative you will not need to wonder if someone else has cast a spell on you, because your own magic will be balancing your life.