(NSFW) Partner sometimes puts less effort into giving?

Sometimes (like tonight!) I feel like my partner isn’t putting in any effort when giving me oral sex. I asked for oral tonight, so I could use all of the new advice I’ve been given, but it wasn’t that good. His heart just wasn’t in it tonight I guess.
When receiving, do you feel like your partner is putting is less effort.
When giving, are there time you put less effort into giving your partner oral sex?