I wanted to chip in after chatting with nhgrif. Consider brainfuck (BF for short). Examples from Wikipedia.
So, BF is purposefully designed as obfuscating. But it can be made sense of using comments and such, and BF has been on-topic assuming other question guidelines are met. We've even had some popular BF questions, like this one or that one.
That being said, BF could very well fall in the "code golfing" category due to its nature. For instance, a question like this would extremely likely be closed as off-topic:
Print "Hello World!" in BF
This code prints "Hello World!" to console. How can I make it better?
++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.
As opposed to a question that could very well be on-topic, such as:
Print "Hello World!" in BF
This code prints "Hello World!" to console. How can I make it better?
+++++ +++ Set Cell #0 to 8
[
>++++ Add 4 to Cell #1; this will always set Cell #1 to 4
[ as the cell will be cleared by the loop
>++ Add 2 to Cell #2
>+++ Add 3 to Cell #3
>+++ Add 3 to Cell #4
>+ Add 1 to Cell #5
<<<<- Decrement the loop counter in Cell #1
] Loop till Cell #1 is zero; number of iterations is 4
>+ Add 1 to Cell #2
>+ Add 1 to Cell #3
>- Subtract 1 from Cell #4
>>+ Add 1 to Cell #6
[<] Move back to the first zero cell you find; this will
be Cell #1 which was cleared by the previous loop
<- Decrement the loop Counter in Cell #0
] Loop till Cell #0 is zero; number of iterations is 8
The result of this is:
Cell No : 0 1 2 3 4 5 6
Contents: 0 0 72 104 88 32 8
Pointer : ^
>>. Cell #2 has value 72 which is 'H'
>---. Subtract 3 from Cell #3 to get 101 which is 'e'
+++++++..+++. Likewise for 'llo' from Cell #3
>>. Cell #5 is 32 for the space
<-. Subtract 1 from Cell #4 for 87 to give a 'W'
<. Cell #3 was set to 'o' from the end of 'Hello'
+++.------.--------. Cell #3 for 'rl' and 'd'
>>+. Add 1 to Cell #5 gives us an exclamation point
>++. And finally a newline from Cell #6
In this regards, I think questions that are specifically golfing (i.e., obfuscating) should be off-topic for Code Review.