Affiliate Declined - Ignorance (IMHO)

In order to generate a little more money, hopefully, I have begun applying for affiliate programs and have acquired quite a few links as of now but have been declined by several others whom I thought would really be no problem. I was wrong. Apparently, for whatever reasons that aren't specifically detailed, my application was declined. I have been sitting here, a bit insulted but not much. I have been wondering more what their reasoning could be to turning down free advertising? I chose programs which were relevant to my site, my sites are not ADULT nor are they controversial so what would it hurt to allow me to put up a banner to advertise for them?