This post is older than a year. Consider some information might not be accurate anymore.
If you create your own rpm, you may make mistakes in the scrips of pre and post installation and removal. Especially removing an rpm with a wrong pre-uninstall script is not possible, e.g removing a folder that doesn’t exists. For that case you can erase the rpm with the
rpm -e --noscripts my-rpm-1.0.0-85.noarch
After that clean up manually.