Eroticism is Degrading to Women

There seem to me to be at least three different kinds of erotic visual (pictorial) art, reflecting three different intentions or purposes:
to cause sexual arousal;
To portray or capture some element or aspect of sexuality or sensuousness;
or to express or communicate something in pictorial form about sexuality or sensuousness, often some insight the artist has about it.
Of course, one work may incorporate all three of these features; a picture may be arousing, may capture some essential aspect of sex, and may make some sort of statement about sex. In fact a picture / art may be arousing because it captures some exciting aspect about sex or sensuality.

Not all Eroticism is Degrading to Women

There are some areas I can immediately eliminate from good erotic art - those which portray degradation, humiliation, or treatment of people as merely objects with no consideration for their feelings, and those which portray any sort of pain, brutality, or violence in some manner that tries to extol or equate it, or tries to associate it in some positive manner, with sexuality.
Now some feminists regard all erotic art, by its very nature, as degrading women; but I doubt this is a fair assessment, since
(1) Some women themselves who have a good self- image enjoy looking at and/or posing for some erotic images.
(2) Some men who respect and think very highly of women like to look at some erotic art without therefore thinking any less of the women who pose for it or of women in general.
(3) If sex and sensuality are something both men and women can find wonderful and/or can enjoy equally, then I see no reason why art which deals with it should by its nature be one-sided or degrading to one sex.
Some artists even seem to consider some of their work as an effort to elevate in the mind the sensuousness of women, or at least as an effort to capture or portray the sensuousness of a particular woman or women in general. And they do this for the same kinds of artistic or communicative (or whatever) reasons that one might try to capture, point out, or express any human quality, emotion, or insight.

The Art of Eroticism

So I think one element that can contribute to erotic art's being good is its capturing or portraying some of the things that might make sex good, such as the joy and/or pleasure it can cause, such as the excitement and the calm it can bring, such as its sometimes gentleness, such as its allowing a communion or sharing of spirits or feelings or moods, such as its art to allow the simultaneous giving and receiving of pleasure, and any of the vast variety of things there are that make sex sometimes a wonderful, erotic artistic experience.
Since many of these things are themselves felt experiences or felt impressions, and not visible characteristics, capturing or portraying them visually can be quite an art or intellectual accomplishment. And, except for cases of extreme artistic luck, it requires some sensitive awareness to their occurrence in the first place.
... Visual erotic art is often bad because it either does not capture any of the better essences of good or interesting sex or it does not portray them well visually (due to either technical or artistic reasons i.e., bad lighting, bad composition, bad cropping, bad exposure, etc.), or it overrides good portrayal of these elements by featuring other elements that spoil or ruin the overall effect, such as pain, violence, humiliation, apparent one-sided "use" of one of the participants, terrible consequences for the relationship, or whatever.