If want to throw away your source-code after writing it, it's OK to ignore styles. That applies for fast scripts, that you make for your task, that really runs only once. On the other hand, how often it happens, that the task that was supposed to run only once will be reused later.
Reusing may be OK, but it will later hard to understand what happens. If you want to modify the code later, you are lost without some style.
How important a proper styling is, depends on how long you will use and modify the code and how many will work on it.
If you work in a team, speak about which styles should be applied.
