Unfortunately, ever since then, except for her great success at keeping the case in the public eye, Beth has been her own worst enemy.
By making dozens of claims that are inaccurate, hearsay, inconsistent, or in which she states her opinion as fact, Beth has repeatedly shown herself to be an unreliable source of information. While she is certainly well-justified in suspecting Joran, in her arguments against him and the Kalpoes, she has pursued essentially a battering-ram approach, repeatedly demonstrating an extreme lack of objectivity and critical thinking, in particular an inability to adjust her opinions based on new information. Within weeks of the disappearance, Beth had formed certain opinions, from which she has never wavered: That Natalee was drugged and kidnapped, was sexually assaulted by Joran and the Kalpoes in the car while going "in and out of consciousness", was taken to Joran's home, and was sexually assaulted by him there. And Beth has frequently promoted these ideas in her public appearances, even though they are all completely unsupported by any evidence, and some even fly in the face of such scientific evidence as phone and computer records.
An example of how Beth needlessly undermines her own credibility, by stubbornly pushing her unsubstantiated allegations, is her decision to subtitle her book "The True Story of the Aruba Kidnapping". There is no evidence that Natalee was kidnapped, and the book itself mentions the "Woohoo, Aruba" incident that indicates she was a willing passenger.
Throughout this case, Beth has automatically embraced any claims that seem to incriminate J2K (even if they are not always logically consistent with her stated beliefs about what happened), regardless of their reliability, and continued to repeat them, even when they are debunked or retracted. Examples include her hearsay accounts of Deepak's car being spotted at the Van der Sloot home before the Alabama group first arrived there, and of Paul van der Sloot stating he picked up Joran at McDonald's, at 4:00 am on May 30 (aside from being incompatible with the phone and computer records, it's unclear how such a 4:00 am pickup would be consistent with Natalee having been being left with Joran at his home). Additionally, Beth has maintained that blood was found in Deepak's car, even after Aruban authorities retracted those reports. Apparently, Beth prefers to believe in a cover-up, rather than accept the much more likely innocent explanation, that the changing information was just another instance of ALE incompetence.
Then there is Beth's continued endorsement of the infamous Skeeters tape (the primary basis of her "gang rape" accusations), long after it became apparent that it had been dishonestly edited to change the meaning of what Deepak said. Although in fairness, while at that point Beth should have distanced herself from the tape, she also should never have been placed in such a position. I actually see Beth as the biggest victim of the Skeeters tape fraud.
Also, with the exception of the first few hours after she landed on Aruba, the quality of Beth's investigative efforts has been dismal. For whatever reason, she has clearly never made anything approaching a systematic effort to contact and debrief all the MB students on the trip. Instead, it appears she has speaking mostly to just a small number of Natalee's close friends, and not even questioned them very thoroughly. Her seeming lack of curiosity about the details of what the students may have witnessed, has been remarkable.
The explanation may be that she is someone who operates largely on gut feelings, and hence is less concerned with the specifics of exactly who saw what, where and when, as with larger "truths". For example, since she already "knows" that Natalee was kidnapped from CnCs, she isn't as motivated to question witnesses, in order to piece together the precise sequence of events. She may even be subconsciously trying to avoid learning anything, that may challenge what she prefers to believe.
And finally, since the disappearance, Beth has consistently shown some very poorjudgement in who she trusts and associates herself with: It seems that nearly every one of her chosen allies has shown themselves to be incompetent, dishonest, or even criminal. The latest example, is her bizarre romance with John Ramsey.
Of course, Beth is after all just the victim's mother, not an attorney trained to be factually precise in her statements, or a professional investigator with the duty and the experience to be objective and analytical in her thinking. But for those who consider themselves among her supporters, and have concluded she is most likely correct about Joran's guilt, yet aren't willing to blindly accept everything she says without scrutiny, much of Beth's behavior can be extremely frustrating.