It really depends on how the compliment is presented. Ex. "Dang girl you are hot" vs "You look nice this evening" Some females would say their is nothing wrong with either, but some would consider the first having sexual undertones.
In the work place it is very dangerous and should be avoided. What you say and mean as a complement could be misunderstood. Sexual harassment is real and you do not know how you message will be received. I do not like it but better be safe.
No its not a bad thing, it can actually help people's confidence level just be careful how you word things:D however complimenting every girls look will make you seem like a player and then girls may not feel you know that pretty after all