apollo00

So, I'm not clear where you're based and I only have experience of this in the UK, but my opinion is you'll have precisely zero luck seeking compensation for lack of cleanliness based on the pictures you've posted.

If the seat was sufficiently dirty that it soiled your clothes or similar then you'd have a clear case (for dry cleaning bills or replacement if that was not possible) but what you've shown is a small amount of uncollected rubbish and some (appears to be dried) liquid in the bottom of a bin which likely didn't affect you materially.

Also, did you ask to move to another seat?

I'm not saying it's acceptable or pleasant but I also don't think it's grounds for demanding compensation. If you feel strongly then complaining to BA and making clear you would avoid their service in future is probably the only real avenue open to you here (and frankly, unless you have status or are a frequent customer then they may just shrug and give you the 'sorry you feel that way' email)

I'd stick to the meal if I was you as that's a more concrete failure to deliver something, though again, if you went to small claims and BA said 'we offered you a special meal compatible with your dietary requirements and you declined' then you might well get nothing.