Following are some of points developers should take care off.
- Bad coding
- Not following standard
- Not keeping performance in mind
- History, Indentation, Comments are not appropriate.
- Readability is poor
- Open files are not closed
- Allocated memory has not been released
- Too many global variables.
- Too much hard coding.
- Poor error handling.
- No modularity.
- Repeated code.
- Miss use of things (tools, concepts)
- Compromising security
- Reinventing the wheel, if some thing is already available in gem/code you create once more
Note: Comment about more bad coding, so that we can create a list of do’s and dont’s