sloppy solder job by builder? - replace section of copper pipe?

[lbspartx]

Hello all, I want to add tees to my hot and cold 3/4" supply lines located in the wall of my garage for a utility sink. I was going to use sharkbite slip tees but one of the lines is really messy on the outside where I want to add the tee. Here are my questions:

1) Is that just a really bad solder job for the coupling done by the builder? see close up view in first attached picture. The crap on the outside appears to be solder.

2) Should I just replace the bad/messy section of pipe (see second picture showing section to be replaced) with the tee added? If so, can I use sharkbite and pex for that? I don't have experience with soldering which is why I'm wanting to use sharkbite fittings.

The third picture shows my overall plan:
1) location of rough in for hot and cold supply (1/2 pex) to utility sink - to be located 18" from the floor
2) replace messy section of supply line (see previous questions) with tee added for cold water supply - run 3/4" pex through stud to next stud bay
3) sharkbite slip tee for hot water - outside of pipe is clean so using sharkbite shouldn't be an issue.
4) reducing elbow from 3/4 to 1/2 pex
5) connect sharkbite 3/4" slip tee to sharbite reducing elbow (3/4" to 1/2") using a short piece of 3/4" pex (doesn't seem like the best solution - is there a better way to do this?)
6) ty into main sewer stack for sink drain.

Any suggestions how how to do things better?

Thanks in advance for any help.

 

[breplum]

Yes, really bad workmanship on soldering, including not wiping flux residue resulting in verdigris.

Use a AAV (air admittance valve) for the utility sink vent.
I've never used sharkbite slip tee so can't contribute there.
I'd recommend finding a local one man shop or retired plumber to come ProPress what you want.

 

[pasadena_commut]

Yes, really bad workmanship on soldering, including not wiping flux residue resulting in verdigris.

Makes me wonder how bad the inside of that pipe is.

 

[RickFlorida]

That's probably the worst soldering job I've ever seen. Wow. I'm not surprised it's Texas. No offense but I heard Texas has the least amount of codes and builder standards. But in Florida, we have the same underlying problem with new home construction. And this is why I love my 1957 house that was built like a bomb shelter. The underlying problem is that today, developers just sub-contract the work out to god know's who. You have so many different people coming and going and don't work together. In the older days, the same guys would build a house together and have to have higher standards when they rough in things for their coworkers. The race to greed has killed everything.