Hi dude,
Before judging the quality of info on a site, it helps to first find out as much as you can about the site. If you click on 'home' and then scroll to the bottom of the page, you often find a lot out; usually who is running the site and some details about it. If there's nothing there, look for a button labeled “who we are” or “contact” or similar.

When I do this with the example site above I find a disclaimer. That tells me it's probably a private site but it's concerned enough about TE rules to put that disclaimer there.
In 'contact' I find a nickname on the email address: “Remedy solution”.
When I run this through the site's own search function I find three posts by “Home remedies solution” and I'm guessing that this is the person behind the site who puts up most of the info.

Next you look at the info. Your post showed me some of it, the fact that the site calls Lentigo “Age Spots” tells me that it's aimed at the general public rather than scientists. And that almost always means that the content will be well-meaning and not deliberately misleading, but often wrong.

It looks like most of the info in this case was copied out of a home remedies book (or more likely several different ones) so its veracity will depend on how up to date those original sources were, and anything looked up here will have to be cross-checked against other sources for confirmation,  consequently this is what I'd call a “medium-useful site”; similar to Dr Mercolas or Lynn Mc-Whatshername's site here: http://www.wddty.com/

If you collect your own bookmarks of reliable sites, do share. This sort of Sherlock-Holmes-Type Analysis takes time out of actually learning stuff  :  ) But stories such as this:
http://www.the-scientist.com/blog/display/55671/
remind us to always remain on guard and question everything we read.

To revisit the original subject of your enquiry, Lentigo are not caused by age per se but by cumulative skin and immune system damage. It's really important to discern the difference between malignant Lentigo and benign Lentigo, and that's one reason why seeing a skin specialist when they first appear is important. Lentigo on the face or that have changed their nature elsewhere on the body are particularly important to get diagnosed right away.

Once you know they are benign (and almost all lentigo on the body are benign, thank goodness), there are multiple ways to treat them and to prevent more from forming. As always, methods focusing on prevention (for example based on diet and strengthening the immune system) are the most successful in the long term.
Best,
AR