I recently used Tile Perfect's "Spray On" Grout Sealer. It came in a 15
oz. aerosol. Bought it at Home Depot.

I used it to seal the grout in ceramic tile floor (kitchen and bathroom).
The tile is white with a bit of a pattern. The grout was beige/sand
colored.

No problem with application or fumes. The directions advise that the over
spray on the tile will evaporate. I did wipe up some areas where the spray
had pooled a bit but no extreme measures otherwise. I ran some floor fans
to speed up the drying process.

No discoloration of the tile or the grout. I did initially have some areas
where the grout was slightly darker due to over application (an 'oh sh*t'
moment for me) but 24 hours or so later the grout coloring was consistent.

I did test the sealer in an area before applying it to the entire floor. I
would use the product again.

Having said all of that, I haven't had any major spills so I can't attest to
the sealant's ability to repel stain.