Hmmm... well, it's important first of all to remember that the emotional health/maturity of an individual is more pivotal to how liked or disliked they are than their MBTI type. I think it's just that there are some personality traits of ISFPs that tend to manifest themselves in unhealthy specimens of the type, that can be particularly annoying.
Take my mother, for example. She is a case study in the unhealthy ISFP. I love her to bits, and she is my mom, but she is batshit nuts
and some of her traits are shared by other unhealthy ISFPs. For instance
- she's incredibly flaky. There are several things I mean by this term, but to begin with she has not got a practical bone in her body. Organisation of any variety is an unwelcome obstacle to her plans, and she does not appreciate the necessity for planning anything.
- I think when people describe ISFPs as selfish, what they really mean is more... self-centred. there is a distinction, in my mind at least. It's not that my mother sets out to hurt people, but she doesn't really think of them, either, and this can be endlessly frustrating. The way she acts, speaks, etc is very much centred around her needs, her ego, with minimal consideration being given to others. Perfect example: she sees rules as "guidelines". She was in an arboreum recently and started cutting off branches, twigs etc from rare bushes/plants despite the big sign on the wall saying "NO CUTTINGS". She wants the cuttings, so she takes the cuttings. Never mind that the plants in question are rare, she is not an arborist and may harm the plants, they're incredibly expensive and you can't just TAKE them, and my poor dad was mortified. She wants it, she takes it. Simple as.
It was the same with my ex, who was also ISFP. Nicest, most harmless guy ever, but very much also wrapped up in himself. It just never *occurred* to him to really consider others the way it does to me. I do it every time I take a step, but for some reason... I dunno, it was like he lived in his own little him-centric universe.
- She (my mom) has no, and I mean NO sense of personal responsibility. If it doesn't feel good she just won't face it. She's interested in personal development/philosophy/therapy etc ONLY up to the point where she has to engage in critical personal assessment. If you tell her to love herself, be kind to the world, be one with nature, blah blah blah... she'll listen, but tell her she's being unfair/irrresponsible/nasty and she will just point blank refuse to engage.
I could go on, but i'm aware that my mother is a remarkably unhealthy example of an ISFP so to continue along this line would be unfair to the rest of you. On the upside, you can be incredibly gentle, good-natured people, and even my mum, I love very much. Those are just the particular shortcomings of your kind when the specimen is emotionally poorly developed.