Is one obligated to accept a wedding invitation when some of those invited are letting their garments hang below their ankles (musbilin), or have shaved their beards (haliqin), or are smokers?

Responding to a Muslim's invitation is obligatory, unless it involves a forbidden act (munkar) or a legitimate impediment that permits non-attendance. The presence of some disobedient individuals at the invitation is not an impediment. If the invitations become numerous, making it difficult to respond to all of them, or if it distracts a person from their private affairs, especially for public figures, then they are permitted to decline the invitation, while offering an excuse to the inviter if possible.