If your mic is doing its job—making you sound like YOU—then other than a bad recording environment bringing in bounce or echo from within your recording area, or extra noises outside your booth, like from your dog, kids, passing trucks, or your refrigerator—don’t blame the mic.
Now, the mic could be too sensitive for your recording space and be hearing every snap, crackle and pop coming from your ear-nose-throat, your chair, your clothes, as well as the mice scratching themselves across the street. So, there’s that. (Solve this by setting up your space first and matching the mic to it, instead of the other way around.)
You can (and should) have your sound checked by audio engineers, local or online, to make sure, of course. But before you rush out to buy some new mic, consider your performance. It’s something we all have to work on constantly. And then again, you may be doing just fine with that, too.
Keep getting coaching throughout your VO career. It’s a fact of life in the performing arts. We get into ruts, stop hearing issues, and just need the reboot from time to time.
Then again, it could just be that you weren’t the voice the client had in his or her head. And there’s nothing to be done about that. Don’t take it personally and don’t blame your gear. Just keep working on your craft, keep auditioning, keep marketing and find your niche and new opportunities.