I don't think
@totalspurs is saying the booing was racially motivated in and of itself - those that booed were motivated to do so by the belief that Sanchez is a rubbish player who should not have been subbed on, and then compounded when he made mistakes, those mistakes leading to more booing. That was the motivation. But it is fair to ask whether 'we' (i.e. anyone) might react differently to people based on certain characteristics - race might be one, but it could be class, age, weight etc - anything that might lead to a more biased reaction towards one individual that might not be applied to another individual doing the same thing, even if not deliberately so. I don't think it is something that can be applied en masse - it's up to individuals to think about whether they would treat others doing the same thing in the same way and if not, why that might be.
As an aside, I do feel that the phrase "playing the race card" also damages the fight against racism (and can be quite insulting - it's not top trumps) as it's too easy to use to put someone down, rather than ask why they believe they are a victim of racism.
Anyway, not wanting to derail further, I hope that there has been sufficient discussion amongst Spurs fans of what happened on Saturday that Sanchez won't get booed if he plays again. If Lenglet is out, we may need him.