Grapefruit is disliked by many and I do not blame you on occasions. Some fruits are quite fibreous which makes them chewy. Also they are sour. Yes they should have that scratchy? back of the throat flavour but they do not have to be sour.
We frequently see pictures of perfect shiney yellow balls and with this picture in mind that is what we buy. We have forgotten this food grows in the natural world. It needs time to be nourished by the parent tree and during that time the sun shines strong on the skin, the wind blows and knocks other twigs and branches against, sometimes hailstones! The skins get marked. Because we think we want perfect looking fruit the growers will harvest too soon and what we get is perfect yellow plastic balls. Good to eat fruit needs time.
Interestingly grapefruit does help when you are on a diet. They do not know exactly how but it is a fairly potent product and for this reason some people on specialised medication have to avoid it. It is not that there is anything dangerous about the grapefruit it is simply that the fruit interfers with the way the drugs are absorbed in the gut and the drug becomes too toxic.
The grapefruit I recommend at present is the Florida pink or ruby ones. They are thin skinned, tender and sweetened. Later in the season Cyprus Yellow grapefruit can be eaten like an orangeBack