JMO, indeed, but my experience is like Thomas'. I've seen them turn up and just as quickly disappear. I consider them somewhat of a bloom animal...I've seen them here and there. Turned up in an LFS system I worked on but were gone pretty soon. Now I reckon they could become some plague, but I am much more likely in this hobby to take this slow and sure instead of drastic (unless measures warrant it - eg someone has parasitic cirolanid isopods or something...but when a small crustacean comes out, bites you and draws blood as well as kills all your fish, well that is reason to act a bit faster). Things crawling around on the glass at this time are not reason to nuke your LR $$$ with fresh water.
However, cutting back on feeding may be good advice for anyone. Often new tanks are overfed so it is worth questioning that...but I don't think it is a critical thing in regard to this issue.
A picture is also helpful....but I know these would be difficult.
But "dots with legs" are generally these things -
"Tiny ants on glass" are generally copopods (they can usually be seen moving) -
"Tiny hard spiral things" are the worms Thomas showed above -
These are probably the top three small white things people suddenly see on the glass.
