I love this topic because I love spells. I have been known to search for a spell to suit my needs but once I find one I always tweak it to suit me and my unique situation.
A spell is so much more powerful when it is personal. Without that personal connection I don’t believe that things work quite so well and if you don’t know the person who created the spell you really don’t know too much about it other than what they tell you.
I like to use spells that I find online as a jumping off point. I prefer to research correspondences, moon and astrological phases and everything else I can to make sure that my spells suit my intended outcome. A spell is only as good as the work you put into it yourself –at least that is my opinion.
So I see no problem in using spells that you find just use them with caution, research their components to make sure they are for the intention stated and then tweak it so that it is meaningful to you.