I often agonise of this, especially on a CV. e.g. I know how to use (say) a certain programming language a lot better than people I know actually being paid to use said programming language as their full-time job. On the other hand, I know my knowledge is really quite limited and no where approaching an experienced developer--certainly at present I could code up a smaller project or a prototype, but probably no more…
It is accurate and conveys a certain flexibility and curiosity to the reader, assuming they are putting any thought into reading it.