tub pipe drainage

where the bath tub drain and p- trap I removed from my old tub was screwed onto the rest of the pipe going to the main drain (this is on the 2nd floor) there was some waste water that was pretty scuzzy. The tub/drain had not been used for over 6months, but I am wondering if the pitch of the pipes were correct should there be any water in this part of the pipe? I am wondering if I can just try and attach the new drain for the new tub and a new/clean p-trap connected where it was or if I might have a slope problem

If this doesn't make sense let me know and I will try to explain it better.

Jane

The trap could have had some water in it and when you removed it, some of that could have gone down the drain and wetted things. Also, it's not uncommon for there to be some soap scum there. Condensation is also possible in the pipes, especially as you go up and get closer to the exit towards the roof and things cool off. All the hot, moist air from draining a tub, sink, washing machine, etc. goes somewhere and some of it will condense. Most does down the drain, but some could accumulate there and keep the soap scum and hair deposits damp.

That line should be sloped from the outlet of the trap to the vertical drain line...IOW, it should slope down all the way from the outlet of the trap.