mark,
blemish, stain, smudge, speck, dot
pimple,
pustule, boil, blackhead, whitehead, blocked pore, zit (slang)
bit,
soupçon, tad (informal), touch, smidgen (informal), dash
place,
location, site, setting, corner, situation, position, point
advertisement,
advert (UK, informal), ad, commercial, plug (informal), promotion
predicament,
mess, difficulty, awkward situation, quandary, plight