Telling the difference between someone who is lonely VS someone who has genuine interest in you?

Peoples always say that if a person really likes you they text you. They make time for you. They call you. Go out of their way to see you. While I do think if someone DOES NOT DO THIS it does mean they do not have a high level of interest in you or an interest at all, but Im not sure if someone doing this automatically means they have genuine feelings for you.

I know people who chase others because they are lonely and just need someone....no matter who it is. People who will text and call you all day because yes they want your attention, they want to be with you but more specifically they just need the attention from someone. Or maybe they are not attention hungry or lonely. Maybe that is just their personality...they are just affectionate and loving and were raised to be very free with their emotions and affection. Not that anything is wrong with this, but I feel like I need to know how to differentiate someone who acts like this due to loneliness (or are just naturally very loving) VS. someone who gives you affection because they are really head over heels for you.

I feel its easy to tell apart attention someone gives you when they want something such as sex, money, or favors from genuine interest but its not so easy to tell apart affection that is given because they are lonely and attention hungry vs attention that is given because the person is genuinely dazzled by you. Especially someone who is just lonely. Because they really do want you attention and affection...Only it has nothing to do with you as a person only to do with filling a void for them....and anyone can do it.