* Types in Rust use prefixing to create derived types whereas C family languages generally use postfixing. A pointer is i32, not int; an array [i32; 5], not int[5], etc. This makes special characters appear more heavily at the beginning of the scan line, and probably makes them slightly more noticeable as a result.

* Lifetimes have the form 'a, and that single quote is likely to bother a lot of people (I know it bothers me).

* Unqualified name lookup in Rust is a bit weaker than other languages, which makes the scope operator (::) more common.

* Passing in explicit generic type arguments for a function requires an extra :: for seemingly no reason.

* Similarly, macros require an explicit ! in the name to invoke. Given that println! (and formatting in general) is a macro and not a function, this means you get a lot of extra uses of ! that's unexpected for C family code.

* Again, the try operator (also decently common) is another random special character.

* Attributes also use #[] syntax, or sometimes #![]. While C++11 did use [[]] to designate its attributes, it's also something that always felt a bit ugly to me personally (I find the @Decorator() pattern from Java or Python to be a visually cleaner way to do attributes).

In short, Rust generally has a higher density of special characters than other C family languages, and I think that contributes to a sense of ugliness.