Do they use pointer arithmetic? This is a good sign. Many "C programmers" just don't know how to make pointer arithmetic work. Now, ordinarily, I wouldn't reject a candidate just because he lacked a particular skill. However, I've discovered that understanding pointers in C is not a skill, it's an aptitude. In Freshman year CompSci, there are always about 200 kids at the beginning of the semester, all of whom wrote complex adventure games in BASIC for their Atari 800s when they were 4 years old. They are having a good ol'; time learning Pascal in college, until one day their professor introduces pointers, and suddenly, they don't get it. They just don't understand anything any more. 90% of the class goes off and becomes PoliSci majors, then they tell their friends that there weren't enough good looking members of the appropriate sex in their CompSci classes, that's why they switched. For some reason most people seem to be born without the part of the brain that understands pointers. This is an aptitude thing, not a skill thing – it requires a complex form of doubly-indirected thinking that some people just can't do.

(c) http://www.joelonsoftware.com/articles/fog0000000073.html

Это, imho, просто яркие частные случаи. Показательные, но не составляющие общую картину.

Про указатели? Возможно. Но учти, что у Джоела очень большой опыт общения с программистами и найма программистов, и при этом сейчас они пишут софт на безуказательном языке.

А вот про 90% of the class goes off and becomes PoliSci majors, then they tell their friends that there weren't enough good looking members of the appropriate sex in their CompSci classes - согласись, гиперболизированное описание того же, что в статье во введении.

Не уверен, но выразить в чём именно сомнение - не получается.