Regarding rub lines: They can be a tremendous source of information. They are one of the prime things I look for when post-season scouting. I especially look for the ones in the thickest stuff around. That may be a place to ambush the big boy.
Regarding scrape lines: I don't know that there is any such thing. Sure, you can find scrapes in a line but usually they are made by different bucks or groups of bucks and mean very little.
However, when you find scrapes in numbers, it is usually an indicator you have some mature bucks in your territory. Although scrapes are used by multiple bucks, the more mature bucks you have, the more scrapes you will have. Unfortunately, 85% of the scraping activity is nocturnal. I believe 99.9% of the activity by a mature buck is nocturnal. I have two scrapes on one piece of property that are open and "worked" throughout the entire year. The activity peaks a week or so before the rut peaks, then drops off. But those scrapes are "used" all year. Even the does use them for communication. One of the scrapes is larger than the hood on my truck. I have never had any indicati0on a buck older then 2.5 has ever been close to either of them.
Now all of that is based on sound research and factual information. But how about this widely believed myth.
A doe unrinates down her legs and into a scrape and walks off. The buck comes along, picks up her scent at the scrape and follows her.
That myth has always made me wonder just how it is that a hunter can believe a "scrape dripper" can be of any value. Yet, a lot of them are sold. Here is a way to make one for nothing.
Fill a plastic bottle with your own urine. Jam a heavy rag in the opening. Tape a piece of wire to the bottom and hang it over a scrape. I promise, it will work as well any one you can buy.