Tangential but related; when I used to work for BigCo, I would get old acquaintances message me on LinkedIn. They would act like they're really interested in my life and I'd interact, and then after a day or two they would ask me for a referral for a job, I'd do it, and then they wouldn't be all that interested in talking to me anymore.
I wouldn't have had a big problem if they had just messaged me and asked for the favor, but I do find it pretty irritating that they're pretending to be my friend just to get a favor. I don't need more friends, I have plenty. Hitting the "refer" button and uploading a resume takes ten seconds of work on my end, but wasting my time with a pretend conversation takes considerably longer.
Nowadays when I ask for a favor from a friend or acquaintance I pretty much immediately ask for it. I might still want to converse with them afterward, but I figure it's better to lay my intentions out on the table immediately so there's no false expectations.