WordPress Plugins are really good for blog in many senses because it enhances performance of blog. But sometimes excessive using WordPress plugins or use of any bad plugin may harm your blog in an unexpected way. There are some factors which should checked out before installing a bad plugin.
Security is a really very serious and important issue. There are many plugins which are threat to your WordPress database that may cause problem in your database. You site may get hacked or your site might get down due to this problem.
Plugins affect other plugin
Plugins are nothing but a series of codes that can enhance your blog by doing certain activities in a database. So it possibly function of one plugin totally dependent on just opposite to another plugin. So one plugin may harm the function of another plugin.
There are lots of people who choose unsecured and unreliable hosting plan without counseling to others. Plugins sometimes enhance the load data on database and it will definitely affect the server speed to load the data. It might be possible due to excessive use of your host; your hosting service may go down. That will be a worst situation for your blog.
Disable or reinstall all the plugins
Sometimes disabling or reinstalling plugin works. But how can we know about the plugin which is really creating problem for a blog. The only solution is disabling and enables all the plugins again. Sometimes it works and sometimes not. The only solution is to reinstalling the plugin via FTP. It will take time to update all the plugins which makes you annoy frustrated.
Support and development
Now this is the most important point: When any developer makes a new plugin, he keeps all the complicity and compatibility involved in the process. Developer try making a plugin compatible to WordPress latest and upcoming versions. In the new version of WordPress, it might be possible that the plugin might not compatible with the latest version. So actually we need to wait for a long time for its developer to update the plugin according to the current version.
What you need to do?
The point indicates only bad plugins which causes the harm to your blog. There are lots of bad plugins available in the market which may harm your blog. So the thing is how to know about these bad plugins. Well, there is no any fix method to know about these plugins, but if you want to know about the bad then you should know about the good first. Good plugins are easy to find and you should see the review of plugins before downloading it. The best way according to me is to go for most popular WordPress plugins because these are the plugins on which most of the people trust.