And they wonder why so many helicopter pilots are alcoholics...
This is a generic response - with 5.4 and four preflights in a 280C, I don't claim to be an expert on that particular aircraft.
The blades delaminate at the trailing edge, where the metal is bonded. They can also delam at the root. While the delam itself isn't usually immediately critical, the problem is first: corrosion - water gets into the blade, and sooner or later weakens the structure sufficiently to cause failure. The water can also enlarge the delam, especially in winter if it freezes.
The second problem is that the delam changes the aerodynamics of the blade. Of course this problem could also be a blessing in disguise, as it provides a possible warning - vibration due to an out-of-track blade.
The aforementioned "tap test" can help find a delam, but is in no way guaranteed to. The best way that I know of is to be fairly religious about cleaning the blades (with a non-corrosive cleaner of course), and visually inspecting them. Any new rotor vibration is to be taken very seriously! If you have the patience, use a magnifying glass to inspect (say every X hours in service).
Finally, as was previously suggested, start your ownership by having the blades inspected by an A&P who is well versed in the Enstrom, and be sure you have the accurate history of the blades. Since they have no TIS limitations, it behooves you to know "where those blades have been"!