Kitchen smell - cobbled together parts?

[Ashman36]

Hi. The house I have moved into last year has had a smelly sink. I now have a chance to look at it and suspect it’s the trap. Dismantling the trap certainly reveals smells further down. I did think it was just an anti-siphon needed. However looking at this again it looks to be a cobble together (pipe in wrong place maybe) of mcAlpine parts which I assume has compromised the seal:

a SK1 standard bowl and half plumbing. Then the trap seems to have been changed and the WM2 hacked into it.

WM2 sink trap with horizontal appliance

It looks like the SK1A might have been the correct part? Any ideas as I assume it’s the hacked together trap causing the issue!

 

[Frelon]

They never work properly when they are plumbed like that!

 

[gpbeck]

Too much pipe work above the ubend, air can flow through and so smells. Best to have a ubend directly under each sink.