A persistent voice warning that some are saving too much for retirement is Laurence Kotlikoff, an outspoken economics professor at Boston University. In a past interview, Kotlikoff, who co-wrote the book Spend 'Til the End -- The Revolutionary Guide to Raising Your Living Standard, Today and When You Retire (Simon & Schuster, 2008) with Scott Burns, put much of the blame on the retirement calculators companies such as Fidelity, TIAA-CREF, Vanguard, Schwab ( SCHW) and T. Rowe Price ( TROW) deploy on their Web sites. "Financial advisers are giving bad advice using bad financial tools that aren't remotely capable of dealing with the question that they are trying to answer," he said, noting that advisers can profit from their inadequate assessments. "The bottom line is that if you over-recommend products, you sell more," he said. "If you get compensated, either directly or indirectly, based on your sales, there is an incentive to make recommendations that are, on average, too high." Kotlikoff, who has crafted his own retirement software tool, ESPlanner, estimates that about 20% of households are likely saving too much for retirement, compared with the 40% he believes are saving dangerously too little.