Different companies and individuals create WordPress plugins and themes, all with their own quality assurance procedures and technical support practices. Some are better than others, and there’s no way to tell what you’re about to get yourself into without testing things out over time first. Market forces are on your side in this regard. Most component authors (a component is usually a plugin or theme), especially those with licensing fees, are keen to make sure their code works as advertised. A component that solves a problem brilliantly but causes problems during upgrades, or has interoperability issues with other components, isn’t going to survive for very long.
Themes and plugins must be updated frequently for a WordPress website to remain secure. Sometimes these updates break a website’s functionality, though reverting to the previous version usually fixes that problem for the moment. Having a testing strategy to profile the component’s stability through the upgrade process is critical before accepting the component for production. This isn’t an activity most website owners will know how to perform or even be aware needs to happen. It is a proactive role that the web designer should own. A WordPress website built with unvetted components is more likely to have stability and security problems. The web designer building such websites is less likely to thrive thanks to a diminished reputation.
The problem of quality assurance isn’t improved just because a component has a licensing fee. The best approach is to hold paid and non-paid plugins as equally suspicious until testing proves they are acceptable for the website in question. Price will be less of a concern in this case since money spent on something that causes problems is never worth it, no matter how cheap it may be.
In many situations, components are more cost-effective than paying for custom programming to get similar functionality. For example, some plugins instantly create a client portal experience. Having such a capability custom-coded by a programmer — including all the quality assurance procedures that go into it — can easily cost thousands of dollars versus a $100/year licensing fee for a plugin. Then, of course, the code must be maintained as WordPress evolves or the threat environment exposes a vulnerability. These are additional, hidden, and unavoidable costs.
Then there is the aspect of accountability by the component author. At its simplest, the concern here is how to contact the component author to get help if something goes wrong.
For a WordPress professional, this is perhaps an even more important aspect of using a component than the problem the component solves. When I evaluate a component on a test server, I try to break it or create a problem on purpose in order to test the response of the authors. These tests help me evaluate both the plugin and the company, or individual, behind the component. I note how the technical support experiences goes, how accurate and timely the responses are, and how many hoops I have to jump through to get help. I also review any public-facing support logs to see average response time and the satisfaction level of the people that reached out for help. This, by the way, is the same test I put any web hosting company through before accepting them as a partner.
It’s been said we are no longer in the Information Age but are now in the Age of Reputation. Social media can flame a poor response from a component author and share that displeasure with frightening speed. Fortunately, the reverse is also true; if someone has a good experience and they share it, a positive snowball effect can benefit the bottom line of the component author.
Whatever method your web designer uses to validate the components they use to construct your website, make sure you understand it. Ultimately, the website belongs to you. In the mind of your clients, you own any of the problems they experience when visiting you there.