The monster is not the problem.
The problem is the shirt that twists under your arm twenty minutes in, right when the movie goes quiet and everyone in the room stops chewing popcorn.
Small misery.

The couch is an honest judge
A bar shirt can lie. A mirror can lie harder.
But a couch tells the truth after one hour, because stiff collars, clingy fabric, tight shoulders, and weird sleeve seams all start asking for attention.
I learned this during a double bill in Pune years ago, in a shirt that looked sharp at 7:10 p.m. and felt like a receipt stapled to my back by 9:43.
So yes, horror clothes matter. Not in a precious way. In a please-let-me-watch-the-basement-scene-without-pulling-my-hem-down way.

Pick fabric before vibe
Vibe is cheap.
Black shirt, white tee, open overshirt, camp collar, faded denim; it all looks fine until the air gets thick and the room starts running warm.
A soft cotton shirt wins more often than people admit. Linen works if it is not too sheer under bright living room lights. Heavy flannel can wait for October unless your friend keeps the AC set to meat locker.
Style and Serum has a useful rundown of men’s shirts that actually behave, and the best bit is the plain thought behind it: shirts are tools first, mood second.
Do not dress like the poster
Please skip the costume math.
A horror marathon does not need boots, chains, a coat with ideas, or anything that makes a plastic chair sound like a drum kit when you move.
Keep one thing sharp. Maybe the shirt. Maybe the watch. Maybe clean sneakers. The rest can calm down and let the fake blood earn its rent.
And if the screening is outside or badly ventilated, remember what Phantom Watchers already said: a summer horror screening is still an outfit problem.
The best fit has manners
Two fingers at the collar. Enough room at the shoulder. Sleeves that do not claw at your elbow.
That sounds dull because it is dull, and dull choices often save the night while showy ones sit there begging to be noticed.
Wear the shirt you forget about. Let the killer doll handle the drama.