Amen to the plastic weld sample being an excellent example...of UGLY.
Now, you are very right Al and I use that example to welders all the time, The code may not define a Pretty weld nor an Ugly weld but I can tell a lot by looking at a weld and assessing it by pretty or ugly. Pretty welds don't need more than a glance and measurement for size. Ugly welds take more time trying to assess rather or not they have overlap, undercut beyond code acceptance, are the correct size, have improper profile, etc. I can accomplish a lot more in a day looking at pretty welds than I can ugly welds. And, truly, once a welder knows how to lay a pretty weld, he can accomplish a lot more in a day than he can when he lays ugly welds. And he won't get as worked up from doing re-work when I/we come by and mark his repairs.
Have a Great Day, Brent