The poor bow tie. It's maligned, misused, punch-lined, and neglected on a daily basis. While it was beloved on young boys through the 50's and 60's, the 80's used it as a prop in movies and television, and in the 90's, you only wore a bow tie if you were getting married or if your driver's license said Louis Farrakhan or Tucker Carlson.
The bow tie also seemed to (unfairly) have stylistic restrictions on it:
professor, curator, or pseudo academic=yes
politician, broker, executive=no
The bow tie would become (and stay as) a prop to denote studiousness, detail, intellectualism, or a safely dosed strategical deployment of non-convention. It allowed the wearer to get credit for daring or deviance without the actual breaking of rules or custom to a degree that would motivate a boss or client to require correction. One can hardly imagine a club, restaurant, or function stopping a hopeful attendee at the door, saying "I'm sorry sir, but bow ties are not allowed."
I generally follow some internal do's and don't's about the bow tie, but they are subtle. For instance, I feel that they are generally acceptable with all suits (including 3-piece), jacket-and-tie configurations, and with sweaters (including cardigans, vests, and yes, crew-necks). The first image below is from the very likable blog An Affordable Wardrobe
They also look intimidatingly fantastic with pinstripe suits and white-collared shirts.
The biggest danger of the bow tie, is wearing it too often. One approaches schtick if it becomes one's thing to wear a bow tie. Once they become a fixture around your neck, you've restricted yourself. Like most things in men's clothing, variation and variety are enriching, and a de facto trademark will diminish the potency of the style itself.
There are plenty of shapes and styles from which to choose. Straight with flat ends and those with pointed ends are more difficult to find.
One problem with bow ties is that the majority of them are adjustable. While this seems like a good thing, the adjustment device is often a terribly unstable mechanism to deal with, and if you're wearing black-tie with a winged collar, the adjuster is on full display, contrasted sharply against the white shirt.
If you know a good tailor or seamster/seamstress, you can have bow ties made for you pretty easily, all in one long piece of silk, and with the shape and ends that you like. I was also given several bow ties that had the middle length (ostensibly an adjuster) removed and replaced with a sturdy and handsome ribbon, leaving 5 or 6 inches of the visible body on either end untouched. Very clever.
One element of the bow tie is that unlike a long tie, it cannot be loosened up during long humid summer strolls... it's either on or off. This tends to be a secretly loved characteristic that bow tie wearers quietly appreciate: commitment to wearing it. The toughest bow tie wearer I ever saw was in a humid piano bar in Zurich during summer. A menacing ox-muscled Alper of a waiter with snug white shirt sleeves rolled well above the elbow insisted that I clap with more enthusiasm to a Billy Joel cover as he refused my 10% tip as too lavish.
The bow tie and long tie are almost always interchangeable, but they are not the same. While a bow tie is rarely incorrect, there are certainly times when one or the other is slightly more desirable to achieve a particular effect or nuance. A judge in a bow tie will be perceived as technically and procedurally minded, not subject to swaying by wild or daring legal arguments. Antiques appraisers, doctors, and accountants are well-served to wear bow ties, as it instills (unfairly) confidence in their ability by the client or patron.
For my toddler son, I often use small pieces of spotted or patterned cloth ribbon for a nice disposable bow tie. Lastly, no pre-tied bow ties. They look terrible, even on children.