Finding agencies that write good research papers
Plagiarism is never encouraged. Buying a paper from a research writing paper agency can get you into academic trouble such as expulsion or failure and the quality of the paper will be less than if you wrote the paper originally by yourself. Finding agencies that write good papers are few and far between. The benefits to finding an agency and using them and having the term paper there do not outweigh the potential risks.
Is it possible?
To even find an agency that had credible writers, the site would need to have detailed profiles for their writers and even in that case, they could lie. Many times the papers are recycled and reused from other clients and therefore, do not fit the parameters and rules for the paper assigned. These recycled papers put together from previous works are also more prone to being caught by plagiarism software.
The silver lining
These agencies can provide a useful resource however. These websites sometimes display sample papers on their sites to entice customers to chose them over another agency. These sample papers are useful for those who are stuck, unsure about how to format a good research paper or even need examples of grammar usage. These would be good tells if the the agency wrote good papers if these were near the norm of the quality received. The sites that even say a paper is custom are not really custom.
These writers do not have to prove capable at writing papers. It would be useful to be able to chat with a writer before any consideration, but any chat service is purely dedicated to already paying customers. Even a money back guarantee does not mean you will find an agency that has quality work.
Research paper writing agency sites are not reliable. There is no way to find a "good" agency without purchasing anything and doing so could mean getting caught and facing consequences. The plagiarism detecting software has made it all the harder to not be caught. The products put out by these agencies are usually recycled and reused papers from past clients and there is no way to interview or see the credentials of any writer for the agency without first purchasing from them. Attempting to find a paper writing agency that writes good papers and buying your research paper is never encouraged. It is, however, encouraged to write original work that will be the quality you most likely would be more pleased with.