Some people are skilled at getting job offers and, therefore, think nothing of starting, yet, another job search that could have been avoided if they had taken the time to research the company that extended them an offer, found out exactly what the position entails, learned as much as possible about the person or people to whom they'll be reporting, discovered why the position has become available, asked to speak with people at the company who have the same or a similar position, and requested the contact information of a couple or, at least, one of the people who had the position, but left the company or moved to another position within the company. I understand that this sounds excessive and am not suggesting that you do all of this before your first interview. What I am recommending is that you don't accept a new position without doing your due diligence.
The reason that I think that it's important to make an informed decision is that, generally-speaking, potential employers aren't impressed by candidates who change jobs every year or two. If they have a choice between a "job-hopper" and someone who has shown more work stability, all things being equal, they'll choose the candidate who is more likely to stay with them for, at least, several years.
Before even going on your first interview, you should have researched the company online and it doesn't hurt to talk with a couple of people whom you know who work at the company. Admittedly, there are very few companies about which everyone has only positive things to say, however, if you hear the same negative comments from, at least, three people who you think are trustworthy, you need to take the comments seriously. You can also look for online reviews about a company, however, you need to take these reviews with a grain of salt as you don't know anything about the people who wrote the reviews.
Before going on your first interview, you should have researched the people with whom you'll be interviewing, assuming that you know all of their names. (Sometimes, if you do really well on an interview with the first person you meet, you'll be introduced to some other people at the company and, since you can't plan for this, you just have to go with the flow.) If you're told that he or she would like you to come back to meet with other people, do your best to get the names of the people with whom you'll be meeting so that you can check them out online. (In most cases, you should be able to get this information the day before the interview if the first interviewer doesn't know exactly with whom you'll be meeting on your second interview.) Very few people business people don't have Linkedin profiles and some of them have Facebook and Twitter profiles as well. Some people reveal more about themselves than others but, at least, you'll find out the interviewers' past work experience, education, groups, and charities or causes that interest them. You might even find that you have some common interests. If you can't research the people before meeting with them, check out the photos in their offices. If, for example, the person is an avid golfer, sailor, etc., he or she is likely to have one or two, or more, photos of that sport.
Since you are, also, interviewing the person or people with whom you'll be working, even during your first interview, at the end of the interview, when the interviewer asks you whether you have any questions, one of the questions that you should ask is "How would you describe what it's like to work for you?" or "What is your management style?"
Once you get a job offer, you can ask to speak to one or two potential colleagues at the company and ask for contact information for a couple of people who have left the company and someone who had the position previously. Sometimes people leave companies for benign reasons, i.e., they're moving to a distant location, they've decided to go back to school, they realize that it isn't the right career for them, etc. It's better to communicate with these people by telephone than it is to communicate by email as you're more likely to uncover the truth by telephone.
The final decision regarding whether to accept an offer should be made by your gut. If you sense that your potential employer is someone with whom you won't enjoy interacting, don't accept the offer. If the work that you'll be doing doesn't interest you or if it's something that you don't think that you're that good at, don't accept the offer.
Admittedly, you might have done your due diligence and find that the position is very different from the way that it was represented to you; the person who hired you leaves and is replaced by someone who is very difficult to work with; you like the position, initially, but, in time, it changes and you don't like it anymore; etc. These things happen and, if you had done your due diligence, you are not, at all, at fault.
The scenario that I described in this post applies, primarily, to people who get into the job market because they're not that happy with their current positions. It applies, only to a lesser extent, to people who are out of work and who are not independently wealthy or being supported by someone else. In that case, people should still do what they feel is appropriate due diligence, however, it is understandable if they accept an offer that isn't up to snuff and continue to look for an offer that is.