Rigid Brain vs. "I am sat ..."

Syntax and semantics matter if you want it to parse without throwing an exception.

Grammar kind of matters. 

Yes, "Grammar ... matters". Thank you!

What bothers me more is ambiguous or incomplete statements. So more of a logic error. It causes me problems as I then struggle to evaluate what it means.

I also don't like when the wrong word is used. I can't help but correct it.

Unless affect is a noun, like in "flat affect".

Or unless effect is used as a verb, like in "to effect change".

They sound more-or-less the same when spoken, so they aren't the worst of my triggers.

Affect is usually a verb, meaning to change something or someone

 "That drug affected me badly"

 "I'll try not to allow emotions to affect my decision"

Effect is usually a noun, describing a change that results when something is done or happens, or a feeling/mood created by something

 "That drug had no effect on me"

 "Joining this community had a positive effect on how I was feeling"

Affect is usually a verb, meaning to change something or someone

 "That drug affected me badly"

 "I'll try not to allow emotions to affect my decision"

Effect is usually a noun, describing a change that results when something is done or happens, or a feeling/mood created by something

 "That drug had no effect on me"

 "Joining this community had a positive effect on how I was feeling"

Unless affect is a noun, like in "flat affect".

Or unless effect is used as a verb, like in "to effect change".

They sound more-or-less the same when spoken, so they aren't the worst of my triggers.