If the person has other credentialed certifications I would say yes. If there are NO other education or certifications then NO!
A general answer about any certification is "will it be accepted where I wish to work". The cost of a program is not the only indicator of its acceptability in the industry, but the cheapest certifications are sometimes cheap because they do not offer much rigor. Call around to a few local places and see what certs. are accepted at a few places you might want to work.
I agree with Ariadne. If you are looking to get a any type of certification (online or not), you need to make sure that certification will help you get the position you are seeking and most important, been recognized by the employer(s) who want to work for. If it doesn't, then don't waste your money and time trying to get certified at that particular certification.
I would think that a certification for Spinning ought to require some real hands on teaching/training.
Often a studio will provide some mentoring and/or additional instruction if you come to them with a certification from a reputable online education provider - not the BS answer 20 questions and you're magically certified once you pay the money. I've worked with these guys for years and the training they provide is very solid http://www.indoorcyclingcertification.com/cycling-fusion/