That's weird - just finished exactly the same job and the walls were also the worst i have ever worked on. I put my 1 metre straight edge on the wall, flat one end for 1/2 metre and at hte other end i could get my whole arm underneath it! Nightmare. The ceiling was artexed and bumps everywhere, the doorframe had dry paint all over it and was bumpy
One of the walls had tiles 1/2 way up, then a dado rail then above had been re-plastered - didn't relise this until i got to where it had been plaster and the tiles lipped out by about 10mm! showed customer and had to take tiles off, strip all plaster back to brickwork, then dot n dab plaster board. That turned out to be the only decent wall. They also had a mosaic border, but couldn't use it as the walls were so bad it would have lipped out in some places and then recessed about 5mm in others.
The floor was also bumpy and unlevel but they were on a budget and weren't prepared for the prep work. I hated this job and my motto is now the old addage
'Failing to prepare, is preparing to fail'.
Not worth the hassle trying to make good on jobs. Anyway, got my cheque this evening, going to pay it in tommorow and learn from this and recharge the batteries!
By the way, i don't think any adhesive manufacturers will gaurentee their addy if you tile on bonding, has to be a finish / top coat. I spoke to BAL Technical and they said it is a wait issue - just a thought