It doesn't matter if the adverts show people training in military style fatigues or combat gear, traditional martial arts clothing, casual sportswear, etc. Does the content of what's being taught seem realistic and will it work for you?

You have to be prepared in a self defence situation to do all necessary, which will usually involve some form of striking or hitting, but does it rely too heavily on striking to make it work? Or is it only striking? This may be fine for someone fairly strong, but can someone of a slighter build do this effectively when their attacker is stronger and pumped full of adrenaline? 

Lots of modern 'self defence' systems use gimmicks to make them appealing. Whether it is quoting a military connection or something from a popular movie, look beyond the surface. A system taught to military or law enforcement personnel sounds impressive, but do military recruits undergoing basic training have the same needs and wants as someone looking for a way to defend themselves in their day to day lives?  

Is using the system's techniques all that is taught, or are you encouraged to escape? Are there methods for de-escalation or avoidance? Is there an encouraged over confidence in the techniques taught?

Anything fancy or complicated wont work in the heat of the moment, are they teaching simple principles? If what they are teaching takes more than a split second, will it really work when needed?

Sport martial arts can be great for fitness, strength and overall confidence. The techniques employed to score a point however may not translate well into actual fighting to defend yourself. In the same vein being able to hit and score a point is very different to being able to hit and stop an attacker, think about this.