It really depends on what case you are dealing with and what state you live in, bottom line is it can affect the amount of the payments . I found this short part that will hopefully lead you to the understanding :
The Uniform Marriage and Divorce Act, first promulgated in 1970, reflects both of these trends. It says alimony should be awarded only if one spouse "lacks sufficient property to provide for his reasonable needs" and, then, it should be awarded "without regard to marital misconduct."
According to the American Law Institute's Principles of the Law of Family Dissolution ("ALI Principles"), published in 2002, twenty states follow this model by refusing to consider marital misconduct when making alimony determinations, while another eight consider it only in rare cases.
Twenty-two states, however, continue to permit full consideration of fault when deciding whether to award alimony and in what amount. North Carolina, for example, bars alimony to a dependent spouse who has committed adultery, and requires that alimony be awarded if a provider spouse has done so. And in every case in which one spouse is eligible for alimony, marital misconduct of all kinds can affect the amount of the award.
Source:
http://writ.lp.findlaw.com/grossman/20050503.html