Some people don't seem to believe it, but you definitely can publish too many papers. The problem is, the surest ways of publishing a lot of papers are to not do many things that are interesting or unusual, and to break everything down into tiny pieces. The first requirement is there because unusual results take time - time for you to believe them in the first place, time to replicate them, time to try to explain and extend them. And no matter what, eventually they aren't unusual results any more - they may still be interesting or useful, but the surprise has worn off, as it has to. So there's no one, really, who publishes a lot of fascinating unexpected stuff all the time, because it just can't be done.
The second requirement is the least-publishable-unit problem, which many people succumb to. After all, if you've got some red-hot results, why wait for the full paper? Bang out a communication before someone scoops you. Trouble is, people bang out communications all the time on things where being scooped is the last thing that could ever happen. As I put it once, many of these things could only get scooped in the sense of someone cleaning up after their dog. Short papers don't stick in the memory very well, either. If the stuff never gets condensed and systematized - that is, written up in some full papers - it's hard to get enough attention for it even if there is something worthwhile stretched across the publication list. It would have had a bigger effect were it not so diluted.
Even famous scientists have fallen into this trap, and I would like to adduce the late H. C. Brown as a shining example. Who, during the 1970s and 80s, did not groan on seeing yet another paper from Professor Brown? Variation after variation on his boron reagents poured forth, each with slightly different characteristics and reactivity, later superseded by other variations in the endless series. And the thing is, there are a number of real advances in there - the man didn't get the Nobel for nothing. But there's an awful lot of work that has, to put it kindly, not stood the test of time. Not everything he and his group did was worth being published.
So if a Nobel laureate can tarnish his reputation by acting like his own printing press, imagine what it does for less famous authors. Be quiet, you feel like whispering to them, be quiet until you've got something to say. . .