The short answer is “No.” In fact, there is significant in the quality of online education today. Accreditation by the relevant governing bodies relevant to the field you may be interested in is probably the most reassuring feature of an online course. However, there are several other aspects you should keep in mind:
1. Could you learn the same for free? The world wide web is absolutely massive so a thoroughly good search about a topic is well worth your while prior to parting from your hard-earned money in exchange for information that could very well already be available out there for free! If it is, then of course you can expect to have to do a bit of leg work yourself compared to the paid course. Often times that is what the coruse material is: a neat compilation the information put together in better-organized, bite-sized lessons. The real value is in the talent of the person who teaches you and guides you through the material.
2. Who is teaching it? Find out exactly what the qualifications of the person or organization teaching the online course are. As in any other situation, you want to know that you are learning from the best! Although an online course which is offered by a very well known university may have better odds of being of better quality, it is by no means a guarantee. In reality this depends on the quality of the program coordinators.
3. Will there be recognized certification at the end of the course? If the course you are taking is specifically to advance your career then make sure that whatever you will be getting in the end will be valued by those in your field.