I understand bode plots, the basics for 1+s, quadratics, poles & zeros, etc.
I do not know how changing the 1+s to s-1 or 1-s as pole or zero will change things. Can someone explain this?

 

If you have (1r/sec)+s, then you have a root at -1r/sec. If you have s-1 or 1-s, then your root is at +1r/sec.