First of all, This is in general, having contradiction does not mean his character is bad. Human are contradictory. One day you act one way, the other day, you do something completely goes against what you did the other day.
Now, after saying that. I'll get into Sanji. Regarding being perverted, that does not mean he's degrading women. That's simply his "sexual drive" being very wild compared to other males.
In today's society, some people look at that as being disrespectful. However, what you need to count is "which culture" are you talking about. Meaning, my culture about the way of treating women is different from your culture, which is different from Japanese culture. And Japanese culture has also TWO sides, there are the modern society, and there is the old society and their ideals.
What some people in one area can be considered as "degrading/disrespectful" can be seen as something "normal" in different culture, or even in the same culture but from different times.
I'll give you an example which happens in other anime to explain more:
If you have seen Bleech, I want you to watch this scene, and then LOOK at what the woman with glasses say (her name is Lisa)
We have the guy being flustered about being called "pervert"
While, the woman in a moment of silent says "it's natural to be interested in woman's body" and act like that.
So, in that scene, you can see the mentality of that woman itself is DIFFERENT from how you view "degrading or disrespectful".
Where, she considers it "normal". And it's only degrading if you actually look at women as "sexual tool". But this is not what Sanji is all about. Sanji simply is a pervert, but he also believes in women, forgives their lies, he is gentle with them, never hits them, sees every smart move Nami does and cheer for her navigation skills. He's someone way beyond a guy who just looks at women as sexual tools for his own desires.
And that's simply my answer.
Also, just to note, in the same society, in the same era, you can find individual women who appreciates a man who lust for them. And at the same time, in this same society, same era, you can find women who hate it and despise it.
Life is never black and white, Life is always grey, it is never totally clear.
And with that being said, Sanji lived all his life loving everything about women as well as being so damn interested in them sexually. That's just who he is. It doesn't mean he degrades them, he is simply a "hyper sexual guy" who's got a boner most of the time LOL
So, yeah. You can live your life thinking that your own way is the ONLY right thing, and the way you are raised is the ONLY way to live life righteously. Or simply, you can accept diverse ideologies, and diverse way of life, and stop being in one single bubble. Women are different, they have individuality. In fact, if I was like you, I can accuse you of being someone who "disrespect women" by giving them one single identity where they ALL HATE what Sanji does. But that's not the case, there are tons of women who hate his actions, just like there are tons who like to have a man who's always lusting for them. To each, they have their own personality, ad way of life. Sanji is no different, he's his own character