I see a lot of the big compaines and everyone in between using redirects or links to one page or another, but how good is it for SEO? I read stuff online that says its no good, bad practice, then I turn around see other people promoting it. I run across domains all the time forsale... great PA, 30k backlinks, but does that really mean anything to redirect a domain like that to my money site? and how do you really validate a domain to be legit... The domain that had 30k backlinks in Moz only had like 3 backlinks in google, somewhat confusing... Thanks
Yes if it's a 301 redirect. No, if it's a 302 redirect. Do make sure that the domain wasn't penalized before otherwise all the bad links will start pointing towards your website as well and you will get penalized.
301 redirect was meant for transferring website/pages from URL A to URL B. But people have taken advantage of this for SEO purposes. Yes 301 redirects transfer link juice, but it also redirects problems like if they're any spammy links. Ideally you would like to find a domain in your niche (similar anchor links) that has all the important metrics. Also don't over do it. Another way is to just create a site with that domain and then link to your site from the content. There are ways to vet domains but I won't get into that.
Yes, if you are an expert, you need to extract the backlinks data and conduct a link audit manually. You could also hire a digital marketing agency who could do that for you. Would you like me to send you the quotations over?
It could either Help or RUIN your website.. Always check two or even three times the backlinks because it can ruin your website if the links are spammy....
The best way to check whether it is banned from google or not. Check site:domain.com in google, if nothing appears for a live site than it is banned. (Even for parked pages)