Is there a word for the feeling one gets around someone who sets off your "spider senses", red flags, warning bells, and so on? I want to say something like, "she made people feel ____." This might happen around a sexual predator, insane person, or someone where something is just very "off", but you aren't sure what it is yet. Is there a word for this feeling? Similar words I can think of are unnerved or disturbed. Is there a closer word?
I would say uneasy.
Causing or feeling anxiety; troubled or uncomfortable [OD]
She made people feel uneasy.
You can omit the verb feel also:
She made people uneasy.
"Skeeves" or "skeevy" doesn't necessarily have any connotations about attractiveness. In practice, it refers to the feeling you describe. It is, however, quite informal, so it's only appropriate in certain contexts. Its slangy nature makes it less accessible (likely why you had to look it up). "Creeps," "creepy," or, as a noun, "the creeps" ("He gives me the creeps.") is similar, although it can have a stronger connotation of fright in my experience. It just depends on the context.
"Misgiving(s)" or "unease" is the word I would choose in this situation.
Definitions from Merriam-Webster.com:
misgiving: a feeling of doubt about something : a feeling that something might not be right or might not work as planned
The "might not be right" application is the key for me regarding the feeling of an instinctual worry about a person.
unease: mental or spiritual discomfort: as
a : vague dissatisfaction : misgiving
b : anxiety, disquiet
c : lack of ease (as in social relations) : embarrassment
Definition C specifically mentions social relations, although embarrassment is not the feeling you describe. "Vague dissatisfaction" seems especially appropriate in the case of a gut feeling about a person who seems outwardly good or normal.
I suggest either:
She made people feel apprehensive
She made people feel trepidatious
Definition of apprehensive in English:
1 Anxious or fearful that something bad or unpleasant will happen:
he felt apprehensive about going home
[WITH CLAUSE]: they were apprehensive that something might go wrong
MORE EXAMPLE SENTENCES
I was very anxious and apprehensive about going in to work.
In the absence of common interests states will be competitive, apprehensive, and even fearful.
Approaching exam time children get apprehensive and nervous about learning and become worried about making a fool of themselves.
Definition of trepidation in English:
1 A feeling of fear or agitation about something that may happen:
the men set off in fear and trepidation
MORE EXAMPLE SENTENCES
For from some deep reaches of my soul, an icy cold fear and trepidation had exploded upward.
Selling a property in this country can be a fraught business, full of fear and trepidation and attended by frustration and delay at every point.
This he did, in fear and trepidation, taking with him two other church workers who were accompanying him.
I'm a bit trepidatious about posting the link to it on here just yet - after all, many projects of mine has risen and collapsed back into ashes in a matter of days or weeks - so I'll give it time to find some legs before I send any readers over to it.
Lyrically, this tells the tale of a trepidatious young bride bidding farewell to her tearful mother on the night before her wedding, in a manner that hints that she might not be entirely thrilled by the prospect.
Round the camp fire, someone joked that killing a goat was trepidatious, hubris in such a holy and mystical place.
(Definitions and examples from Oxforddictionaries.com)
You're looking for "arousal", "a state of arousal" (not to be confused with sexual arousal),
Arousal is a physiological and psychological state of being awake or reactive to stimuli. A condition of sensory alertness, mobility and readiness to respond. Wikipedia
a state of heightened physiological activity TFD
Why not, So and so gave people the creeps? It's the subject who's "off" or repugnant.
But for just one word in that construct, here are some synonyms: worried, anxious, troubled, disturbed, agitated, rattled, nervous, tense, overwrought, edgy, jumpy, apprehensive, restless, discomfited, perturbed, fearful, uncomfortable, unsettled; informal jittery, antsy, trepidatious.