It is becoming common these days among people to preach dropping and picking up a book based on interest, but if you seriously want to express your opinion on the material or the person who has written that, at least try reading it completely before letting your preconceived notions get better of you.

1. ⊕I generally read everything through if I go past the abstract at all. I feel you can't really have an opinion if you haven't read the whole thing; if you don't read the whole thing, and you say anything about it, you are all too often perpetuating lies or half-truths
   —Email Exchange with GwernSeen one way you would be misleading people who trust your opinion and perpetrating a lie that might destroy the credibility of the original creator.
2. And in another way, this is just pure incompetence that is being rationalized as efficient mechanism to imbibe knowledge. Doesn't provide authority, doesn't allow for legitimacy, all it does is allows you to create an echo chamber for yourself where you can engage in a pseudo-random verbal-diarrhea with like minded people.

An example would be this:

"Witness here how salaried physicists are dismissing @stephen_wolfram Wolfram's automata BEFORE even hearing him Just as Freeman Dyson publicly dismissed A New Kind of Science c. 2002; it turned out that he did not read the book. & pple who refused to read it referred to Dyson!"
—Tweet by Nassim Taleb

That said, it should be noted that switching books based on interest is not wrong, caution must be applied while talking about topics that you yourself have not completely gone through.

I'm convinced a lot of leprechauns or 'citogenesis' comes from people who don't read past the title or abstract but decide to cite it anyway as proof
—Email Exchange with GwernGwern describes this better than I ever can by comparing such second-hand partial information mongers to people who use leprechauns or 'citogenesis' based on reading the title/abstract of a paper. (See Below)

Note: Remember any resource that you pick up is someone's sweat and blood. If you do not wish to read it, always make sure not to form opinions on it, or at least not to promulgate any partial information on it. Always try to put yourself in such a situation and see how you'd have taken it — The Silver Rule.

“Do not do unto others as you would not have them do unto you.”

Most of the time our inability to read to completion has to do with association of the act of reading instead of the book that we are read, context-switching can really here. Also Reading with fractalized mental patternReading with fractalized mental pattern
Fractalize your mental patterns instead of reading as a whole (i.e., one single pattern, where the mood of the act is associated with the ego), that way you will be able to selectively associate yourself with a book instead of the act of reading. Most people stop reading when they are bored of reading, but by fractalizing your mental patterns you will be able to dissociate yourself from that particular book and move on to another book instead of stopping reading altogether.


"Be bored with... can be extremely useful in such situations.

References

Conversation with Gwern Branwen. (19-Dec-2019). Email Exchange

…I generally read everything through if I goes past the abstract at all. I feel you can't really have an opinion if you haven't read the whole thing; if you don't read the whole thing, and you say anything about it, you are all too often perpetuating lies or half-truths. I'm convinced a lot of leprechauns or 'citogenesis' comes from people who don't read past the title or abstract but decide to cite it anyway as proof….

Nicholas, Nassim Taleb. (2020). Tweet

"Witness here how salaried physicists are dismissing @stephen_wolfram Wolfram's automata BEFORE even hearing him Just as Freeman Dyson publicly dismissed A New Kind of Science c. 2002; it turned out that he did not read the book. & pple who refused to read it referred to Dyson!"