Fees aren't the only potential pitfall among ETF managed portfolios, says Mr. Hougan of IndexUniverse.

WSJ: When Cheap Funds Cost Too Much

Another potential pitfall to avoid are rooms in a hotel recently converted to nonsmoking.

CNN: Business travelers, avoid these rooms

Another potential pitfall is that higher-end houses are much harder to value than lower priced cookie-cutter dwellings.

WSJ: Castles for the Common Man

One potential pitfall of taking a rescue loan from the eurozone is that it would probably have the effect of subordinating Spain's existing sovereign debt.

BBC: Will Spain suffer an Irish bust?