Back to the original topic, not sure if OP is talking about patty-caking serves in or just utilizing a true "second serve" that is slower and has a lot of spin.
Sometimes when I'm tired, or the pressure of the match gets to me, I'll stop my first serves all together and just serve second serves, but I feel guilty about it and always prefer not to do this.
But I will never just "dink" it over or remove almost all pace altogether. I even try to put some zip on my second serve. I don't feel good winning matches when I tried to be as "gentle" as possible.
i would rather lose a match by starting off @ 100% and finishing at 80%, than winning a match by finishing @ 30% by moon balling it, dinking serves in and drop-shotting everything.